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]]>Light at night predicts increased body weight in women
Studies prior to 2019 of artificial light at night in relation to sleep have major limitations, because they mostly involve shift workers and typically use cross-sectional designs. Researchers in North Carolina used data from 43,722 women participants with an average age of 55 years in the Sister Study to investigate links between various types of artificial light at night and overweight or obesity. At baseline and after adjusting for confounding factors, having light or television in the bedroom predicted significantly higher prevalence of three markers of obesity: waist circumference of 34.6 inches or more (22 percent higher), waist-to-hip ratio of 0.85 or greater (13 percent higher), and waist-to-height ratio of 0.5 or more (15 percent higher). After an average follow-up of 5.7 years, compared to having no light or television in the bedroom, having light or television in the bedroom predicted significantly higher risks of gaining 11 lb of body weight (17 percent increase), increasing body mass index into the overweight category (22 percent higher), and increasing body mass index into the obesity category (33 percent higher). While advice to lose weight typically features increased physical activity and better diet, keeping the bedroom dark during sleep may also help.
Light at night may promote atherosclerosis
Using cross-sectional data from elderly Japanese residents in 2016, Japanese researchers found that higher intensity of bedroom light at night predicted increased carotid artery thickness, a measure of atherosclerosis burden. These researchers extended their earlier work 3 years later with longitudinal data from 989 participants with an average baseline age of 71 years in the HEIJO-KYO cohort. Sensors mounted on bedroom headboards measured night intensity over 2 nights. After adjusting for cardiovascular disease factors, participants in the highest quartile of bedroom light at night (9.3 lux) had significantly greater increases in average and maximum carotid artery thickness compared to participants in the lowest quartile (zero lux) at the end of 34 months of follow-up. By way of comparison, 3 lux is very dim light, too dark to read comfortably, while 10 lux is comparable to a candle flame one meter away. Thus, even relatively small amounts of light at night in the bedroom may promote carotid artery atherosclerosis.
Outdoor light at night may increase risk of coronary heart disease
Emerging epidemiological evidence suggests that outdoor light at night predicts increased risk of chronic diseases. Researchers in the US and in Hong Kong by Sun and others used satellite data to estimate nighttime outdoor light levels at 58,692 residences of individuals in Hong Kong to determine if higher levels of outdoor light at night predicted increased risk of coronary heart disease. After a median follow-up of 11 years and after adjusting for confounding factors and compared to participants exposed to the lowest quintile of outdoor light at night, participants exposed to the highest quintile had significant 23 and 29 percent increased risks of developing coronary heart disease and dying from coronary heart disease, respectively. Outdoor light at night might leak into bedrooms and disrupt circadian rhythms and adversely affect the function of coronary arteries.
An editorial in response to the article by Sun and others supported their conclusions about the harmful effects of light at night. The Sun study was among the first to prospectively examine links between exposure to light at night and coronary heart disease. Authors of the editorial reconfigured tabular data from the Sun study and more clearly showed the statistically significant trend in both hospitalizations and deaths from coronary heart disease in relation to progressively increasing levels of outdoor nocturnal light exposure. The editorial noted that the participants in the Sun study lived in Hong Kong, a densely-populated city with major air pollution, which limits the generalizability of the study.
Experimental evidence that bedroom light at night impairs cardiometabolic function
Exposure to artificial light at night while sleeping may adversely affect metabolic regulation. Researchers at Northwestern University conducted an experiment in which 20 healthy young adults were randomized to either a room light condition or a dim light condition for 2 nights. Dim light was 3 percent as bright at room light. The room light condition included one night of dim light during sleep followed by one night with room light during sleep. The dim light condition included two consecutive nights of dim light during sleep. Measures of insulin resistance were significantly higher in the room light compared to the dim light condition. In the room light condition, participants spent proportionately more time in stage N2 sleep and less time in slow wave and rapid eye movement sleep than participants in the dim light condition. Heart rate and heart rate variability were both significantly higher in the room light condition. In addition, blood insulin levels 30 minutes after administering glucose to participants were significantly higher in room light participants. These findings suggest that sleeping with regular room light may impair cardiometabolic function in young adults.
Light at night may dysregulate circadian clocks
Light at night commonly occurs in developed countries and is linked to adverse health. Researchers at Northwestern University used cross-sectional data from 552 older (average age 72 years) community-dwelling adults in a larger study to determine if objectively measured levels of light at night predicted higher odds of cardiovascular disease risk factors. Wrist-worn devices measured light levels during sleep. No light at night was defined as having no detectable light during the 5-hour period of lowest light exposure. After adjusting for confounding factors and compared to participants with no light at night, participants with light at night had significantly higher odds of having obesity (82 percent higher), diabetes (100 percent higher), and hypertension (74 percent higher). These higher odds may reflect dysregulation of circadian clocks that govern physiological processes, metabolic pathways, and the autonomic nervous system.
Outdoor light at night and air pollution
Chinese researchers used data from 28,302 participants with an average age of 62 years in the Yinzhou cohort to determine if outdoor light at night and air pollution predict risk of aspects of cerebrovascular disease (fatal and non-fatal stroke) over 4.5 years of follow-up. After adjusting for confounding factors and compared to participants in the lowest quartile of outdoor light at night exposure, participants in the highest quartile had a significant 43 percent higher risk of having a stroke. For air pollution, compared to participants who were exposed to the lowest quartiles of PM2.5 and PM10 particles, participants exposed to the highest quartile had significant 41 and 50 percent higher risk of a having stroke. For NO2 (nitrogen dioxide), compared to participants who were exposed to the lowest quartile of NO2, participants exposed to the highest quartile had significant 31 percent higher risk of a having stroke. Alas, the detrimental effects of outdoor light at night and NO2 seemed to be partially additive.
Indoor light at night and diabetes risk
Light at night may increase risk of chronic diseases, perhaps due to circadian disruption. Researchers in Australia and elsewhere used data from 84,790 participants with an average of 62 years in the UK Biobank to determine if indoor light at night measured at the individual person level predicted risk of developing diabetes during 7.9 years of follow-up. Wrist-worn devices recorded light exposure over 7-day periods. After adjusting for confounding factors and compared to participants with dark nights (in the 0-50th percentiles of light), participants exposed to more indoor light at night had progressively and significantly higher risks of developing diabetes during follow-up. Participants in the 90-100th percentiles of nighttime light (most nighttime light) had significant 53 percent higher risk of developing diabetes. Modeling suggested that diminished circadian amplitude and circadian phase that deviated from the group average predicted higher risk of diabetes. Finally, the risk of developing diabetes based on polygenic risk was comparable to the increase in risk from the lowest to the highest scores for light at night. Overall, reducing indoor light at night could be an effective way to reduce diabetes risk.
Bedroom light at night and cardiovascular disease
Light at night disrupts circadian rhythms, which are linked to changes in systolic and diastolic blood pressure, blood vessel function, and heart rate variability. Thus, light at night might increase risk of cardiovascular disease. To address this possibility, the above researchers in Australia and elsewhere used data from the UK Biobank for 88,905 participants with an average of 62 years who wore wrist mounted light sensors for a week. Light exposures at night were grouped in four categories: 0-50th, 51-70th, 71-90th, and 91-100th percentiles with higher percentiles reflecting greater nighttime bedroom light exposure. Compared to participants with dark nights (0-50th percentiles), participants with the brightest nights (91-100th percentiles) had significantly higher risks of developing coronary artery disease (32 percent), heart attack (47 percent), heart failure (56 percent), atrial fibrillation (32 percent), and stroke (28 percent) over 9.5 years of follow-up. Female and younger participants had even higher risks. The increased risks occurred independent of cardiovascular risk factors, such as low physical activity, smoking, and short sleep duration. Sleeping in a dark room may be a novel way to reduce our risk of cardiovascular diseases.
What to do
There may not be much that we as individuals can do in the near term about outdoor light at night. But right now we can reduce the amount of indoor light at night in our homes. For example, we can use an eye mask while sleeping, install dark curtains on our bedroom curtains, use a low-light nightlight, and move the TV out of the bedroom.
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]]>The post A (Behavioral) Path to Eat Better appeared first on Alan T. Carpenter.
]]>Given the massive benefits of eating better, why don’t most Australians (and Americans) eat a healthy diet? What distinguishes people who change their diet for the better and maintain those changes over the long term? Researchers in Western Australia recruited and interviewed 20 residents who self-reported significant positive changes in their diet and who maintained these changes for at least 2 years.
Five themes emerged from 23-72-minute semi-structured interviews. The themes included 1) a desire to feel better, 2) investigation and learning, 3) helpful habits, 4) benefits, and 5) values. The authors noted that more information—simply telling people about the benefits of eating better or the downsides from eating junk food—usually does not lead to better eating.
Desire to feel better
Participants wanted to feel better and thought that dietary changes might help them resolve or at least improve health and weight issues. Desires to improve overall health, reduce body weight, and improve appearance fell in this category. Participants presumably had some degree of dissatisfaction with their current situation that they could rectify by eating a better diet.
Investigation and learning
Investigation and learning refers participants finding information that led them to consider dietary change. Previously, participants often didn’t think much about what they ate, but finding a key piece of information often led participants to realize that what they ate might influence how they felt. While this statement might seem obviously true, some studies suggest that people who eat an unhealthy think that their diet is, in fact, reasonably healthful.
Helpful habits
Participants adopted healthy habits that made healthy eating easier. For example, participants mentioned meal planning, cooking a big pot of stew for multiple meals, eating at home more often, and eating out less often.
The conventional wisdom holds that people with high self-control are more likely to eat a healthy diet because they usually resist temptations, such as overcoming the urge to buy a carton of ice cream at the grocery store. Recent evidence suggests that people with high self-control have developed adaptive habits that largely avoid situations in which they would purchase or consume unhealthy foods.
Researchers in the Netherlands conducted a study in which 77 young, normal-weight Dutch adults (nearly all women) kept a food diary in which they recorded the amount of snacks they consumed over one week. In addition, the researchers evaluated participants’ self-control and habit strengths of eating unhealthy snacks. As predicted, as self-control increased, unhealthy snack consumption and unhealthy snacking habits decreased. In addition, habit strength mediated the relation between self-control and unhealthy snack intake. Thus, developing adaptive habits, such as avoiding the ice cream aisle at the grocery store, may promote a healthier diet more effectively than relying on will power.
B. J. Fogg at Stanford University developed a comprehensive approach to developing new desired habits and jettisoning old undesired habits. His book, Tiny Habits – The Small Changes That Change Everything, focuses on the optimal mix of motivation and ability where behaviors can be habituated with the aid of well-considered prompts. I found the book to be highly readable and practical.
Benefits
Participants started to realize the benefits of eating better, such as improved health and greater mental clarity. Apparently, realization of the benefits of healthy eating likely arose from an awareness of feeling better and linking the perceived benefits to better eating.
Values
Motivation to continue healthy eating reflected a set of values aligned with better health, including participants regarding healthy eating as a new way of life. Values may extend more broadly to ethical concerns related to confined animal feeding operations and the potential environmental downsides of eating lots of feedlot-finished red meat.
Self-determination Theory
The findings of these studies align with three basic aspects of Self-Determination Theory. Richard Ryan and Edward Deci at the University of Rochester in New York spent 30 years developing this body of research. Ryan and Deci have identified three basic human needs that must be met for optimal growth and behavioral regulation. These needs include 1) feeling competent (as opposed to incompetent) to make behavioral changes, 2) having a sense of personal autonomy that we are in charge of our own lives (as opposed to being controlled by others), and 3) feeling connected to other people (as opposed to feeling socially isolated or alone).
According to Ryan and Deci, those of us who have attained these three basic human needs can change our behavior (such as eating better) due to intrinsic motivation (arising from within us) rather than extrinsic motivation (arising from the outer world). Ideally, a person who wants to eat better would feel that his motivation to do so comes from within as a consequence of feeling that he is able to make better dietary choices, that he is in charge of what he eats, and that he is meaningfully connected to and supported by other people.
A lifetime of research by Ryan, Deci, and others suggests that people who live in an atmosphere of autonomy and relatedness and who develop feelings of competence are more likely to be predisposed to make healthy choices and experience a life of well-being than those who live in an atmosphere of external control, social isolation, and feelings of incompetence.
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]]>Knee osteoarthritis involves progressive, irreversible knee joint dysfunction caused by the breakdown of cartilage in the knee joint. The prevalence of knee osteoarthritis is increases with age. The aging of the American population portends increasing prevalence of knee osteoarthritis in the coming decades. Persons with knee osteoarthritis have reduced physical function, decreased mobility, decreased leg strength, and decreased balance. Fear of falling due to balance problems accelerates other aspects of impaired physical function. Guidelines from medical authorities recommend physical activity as the best way to manage symptoms of knee osteoarthritis.
Home-based exercise
Supervised exercise therapy helps manage pain, improve physical function, and improve quality of life for patients with knee osteoporosis. However, supervised therapy might not be readily available for many people given the difficulty of making appointments, traveling to doctors’ offices, and lack of insurance coverage. Researchers in China conducted a systematic review and meta-analysis of 12 randomized controlled trials of home-based exercise interventions to determine their efficacy. All but one of the studies had good methodological quality. In fact, home-based exercise interventions significantly reduced pain and improved physical function with small effect sizes compared to health education or no treatment. Home-based exercise interventions improved quality of life with moderate effect sizes significantly more than did health education. More importantly, home-based exercise interventions led to similar improvements compared to clinic-based and drug treatments at lower cost.
Aerobic exercise for knee osteoarthritis
Little doubt exists that various types of physical activity can help reduce the pain and limited mobility that arises from knee osteoarthritis. Yet, previous meta-analyses of randomized clinical trials suffered from a key deficiency: lack of evaluation of the effectiveness of physical activity interventions over time. A new meta-analysis of 217 studies from an international team of researchers rectified this problem. Outcomes (pain, function, gait performance, quality of life) were analyzed at 4, 12, and 24 weeks after the start of the respective interventions. Overall, aerobic exercise produced the best long-term results with the highest certainty of evidence. Depending on the specific outcome, mixed exercise and flexibility exercise also appeared to be helpful. The meta-analysis authors emphasized the need for consistent, long-term, structured physical activity with help of a qualified health professional to reduce the adverse effects of knee osteoarthritis.
Multi-component balance training
Researchers in China conducted a systematic review and meta-analysis of 22 studies to determine how balance training might be optimized to improve two measures of balance, the Berg balance scale and time-up-and-go. Multi-component training produced clinically relevant improvement in both measures. Specifically, training lasting at least 8 weeks, at least 3 times per week, with sessions lasting at least 60 minutes each produced the greatest improvement in balance for persons with knee osteoporosis. In addition, patients younger than 60 years of age had better results than patients older than 60. The study authors urged clinicians to recommend multi-component training as first-line therapy for their patients with knee osteoarthritis.
Mind-body exercise
Mind-body exercise (MBE) therapy appears effective for treating knee osteoarthritis. However, the relative efficacy of different types of MBE remained unclear. Researchers in China conducted a systematic review and network meta-analysis of 38 randomized controlled trials that used different types of MBEs to reduce pain intensity and improve physical function and quality of life. All participants in the included studies had diagnosed knee osteoarthritis. With respect to reduced pain intensity and physical function, pilates, tai chi, and qigong all significantly outperformed usual care or no treatment with large effect sizes and with moderate certainty of evidence. In addition, both pilates and tai chi significantly outperformed conventional therapeutic exercise with moderate certainty of evidence with respect to pain reduction. Only tai chi showed significant improvement in quality of life compared to usual care or no treatment with moderate effect size and moderate certainty of evidence. Pilates and tai chi were the most effective MBEs for pain reduction and improved physical function, while tai chi provided the greatest improvement in quality of life for patients with knee osteoarthritis
Tai chi online
Studies show that tai chi classes reduce knee pain and stiffness and improves function, mobility, and mental health comparably with other forms of physical activity. Researchers in Australia developed a novel approach that greatly expands the availability of tai chi to seniors – with or without health insurance. The My Joint Tai Chi multimodal on-line intervention (what a mouthful!) includes a 12-week on-line program with one pre-recorded 45-minute tai chi video each week led by an experienced teacher. Participants watch the introductory video three times during the first week following the movements of the teacher. Subsequent weekly videos feature progressively more skillful movements.
The same group of researchers designed the RETREAT randomized clinical trial (the gold standard for scientific studies) to test whether the combination of the on-line intervention plus on-line educational materials produced better knee osteoarthritis results, such as less pain and more mobility, compared to only on-line educational materials. Participants in the study included 178 Australians (average age 62 years) who were recruited on-line and through advertisements. All participants had diagnosed knee osteoarthritis. Half of the participants were randomized to the intervention and educational materials group and half were randomized to the control group that had access to the educational materials but did not to the videos. Intervention group participants were instructed to watch each video and perform the exercises three times each week for 12 weeks without receiving any guidance from the researchers.
Did the intervention deliver the goods? Yes, it did. Compared to the control group, the intervention group participants had significantly less knee pain and greater functionality after 12 weeks. Compared to the control group, more participants in the intervention group achieved the minimal clinically importance difference in knee pain (73 vs. 47 percent) and functionality (72 vs. 52 percent). Finally, the intervention group had better results in 11 of 12 secondary outcomes, such as sport and recreation function, quality of life, and balance confidence. Here’s the best news: The program is available free of charge at https://myjoint-taichi.org. You can also download a free mobile app that helps you stick with the program. While I have not used this program, it comes from a reputable source. If you’ve been diagnosed with knee osteoarthritis, I suggest that you check out this program.
What to do
While osteoarthritis is irreversible, different treatments are available short of knee joint replacement surgery, which has its own risks. If you have knee osteoarthritis, how about trying one of the exercise therapies discussed above?
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]]>The post Circadian Rhythms appeared first on Alan T. Carpenter.
]]>Humans and many other organisms operate on a 24-hour clock. Certain physical, emotional, and behavioral factors change in more or less predictable ways over a 24-hour cycle. Various organs in humans have their own circadian rhythms. Light and dark exert major influence on circadian rhythms. Other factors, such eating, stress, physical activity, social interactions, and temperature affect circadian rhythms, which affect aspects of our daily life including sleep, body temperature, and the release of hormones. Departures from circadian rhythms can affect the risk of type 2 diabetes and other chronic diseases.
Chrononutrition
Chrononutrition refers to meal timing, its interactions with circadian rhythms, and the resulting effects on health. A recent review of the links between chrononutrition and diabetes identified three key messages: 1) meal timing, in addition to meal content, affects type 2 diabetes, 2) a carbohydrate-rich meal at night increases post-meal blood sugar more than the same meal consumed in the morning, and 3) diabetics should be encouraged to consume meals early, rather than late, in the day. My recent decision to stop eating at 6:30 pm after dinner (rather than continue snacking until bedtime) should help keep my blood sugar in a healthy range and reduce my chances of developing type 2 diabetes.
The timing of food intake seems to influence metabolic variables, such as insulin secretion and blood glucose concentration. Yet studies of intermittent fasting and time-restricted eating are controversial, with some studies showing significant effects of metabolic factors and other studies showing no effects.
Morning or evening chronotype
Chronotype refers to a person’s preference for morning or evening activity. Researchers in Boston used data from 63,676 women with an average age of 54 years at baseline in the Nurses’ Health Study II to determine if the evening chronotype predicted increased risk of developing type 2 diabetes during follow-up. Chronotype was assessed with the answer to the following: One hears about morning and evening types of people. Which one of these types do you consider yourself to be? Answers were classified as either definite morning, or intermediate, or definite evening. The study collected data on 6 lifestyle factors (diet, alcohol use, body mass index, physical activity, smoking status, sleep duration). Participants were awarded one point for each healthy lifestyle factor they achieved with an overall score (ranging from 0-6) of 3 or less denoting an unhealthy lifestyle.
The presence of 5 of the 6 unhealthy lifestyle factors (excluding alcohol use) predicted significantly higher odds of participants having a definite evening chronotype compared to a definite morning chronotype after adjusting for confounding factors. In addition, compared to the definite morning chronotype and after adjusting for sociodemographic factors, both the intermediate and the definite evening chronotype predicted a significant 72 percent higher risk of developing type 2 diabetes during an average follow-up of 4.7 years. Further adjustment for the 6 lifestyle factors substantially reduced the risk to 21 percent higher but it remained statistically significant. Thus, the definite evening chronotype, along with unhealthy lifestyle factors, predicted a much higher risk of developing type 2 diabetes compared to the definite morning chronotype.
Chrononutrition and cardiometabolic health
The timing and amount of food consumption relative to daily circadian rhythms appears to affect several measures of health. A recent review arrived at 5 tentative conclusions. 1) Skipping breakfast may increase coronary heart disease, type 2 diabetes, hypertension, and obesity risk factors. 2) Eating breakfast earlier rather than later may reduce odds of the metabolic syndrome. 3) Earlier timing of lunch may lead to better blood sugar control and lower insulin resistance. 4) Later timing of dinner and greater caloric intake at dinner may increase risk of cardiovascular disease and the metabolic syndrome. 5) Increased day-to-day variability of the timing of breakfast and dinner may lead to higher body mass index, blood sugar, and inflammation.
Based on these findings, here’s my approach to healthy meal timing and amount. Eat a substantial breakfast at 7 am after arising, eat a more substantial lunch (the biggest meal of the day) at noon, and eat a modest dinner (the smallest meal of the day) at 5:30 pm. No food after dinner until breakfast. Alas, I’m still tempted to snack after dinner.
Chronotype, sleep, and cancer
A 2025 systematic review included 22 studies that related chronotype, sleep timing, sleep regularity, and cancer. Eighteen of the studies investigated chronotype. Six of the studies reported elevated cancer risk for evening compared to morning chronotype. Yet, 10 studies reported no significant associations. The review found “evidence linking late chronotype, later sleep midpoint, increased social jet lag or weekend catch-up sleep to risk of cancer.” Large differences among studies with respect to sleep measures, terminology, and cancer sites clouded interpretation of study results. The review concluded with the following sentence: “Current evidence linking sleep timing, sleep regularity, and chronotype with cancer risk remains inconclusive.”
Circadian health, cardiometabolic health, and disease risk
In 2025, the American Heart Association issued a Scientific Statement regarding the role of circadian health and cardiometabolic health and disease risk. Circadian health refers to the optimal function, rhythmicity, and alignment of central and peripheral circadian clocks in the body. Circadian rhythms operate on approximately 24-hour cycles and regulate physiological and behavioral processes that synchronize to environmental cues, such as light and food intake. Bodily processes that operate via circadian rhythms include blood pressure, heart rate, body temperature, and blood vessel function, among others. Disruption (misalignment) of circadian rhythms seems to foster adverse health outcomes such as weight gain, type 2 diabetes, hypertension, and cardiovascular disease.
Causes of circadian disruption include shift work, irregular sleep timing, social jet lag (changes in behaviors from weekday to weekend), insufficient early morning light, bright nighttime light, and mistimed eating and physical activity. Individual humans can have different chronotypes, approximated as morning or evening persons. Studies suggest that improved circadian health can arise from improved sleep regularity (including week days and weekends), avoiding bright light (especially in green and blue wavelengths) at night, experiencing bright morning light, eating larger meals earlier in the day, not eating following dinner until breakfast, and aligning physical activity with one’s chronotype. While there seems to be little doubt that circadian health promotes cardiometabolic health, the research base needs to expand substantially to support specific recommendations to achieve optimal circadian health.
What to do
Maintaining regular daily schedules of eating and sleeping might help reduce your risks of certain chronic diseases, including cardiovascular disease and type 2 diabetes.
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]]>The post Forest Bathing appeared first on Alan T. Carpenter.
]]>In 1982, the Japanese Ministry of Agriculture, Forestry, and Fisheries coined the term shinrin-yoku. It refers to making contact with and taking in the atmosphere of a forest. Shinrin-yoku is also called forest bathing in the sense that a person is immersed in the forest, with attendant cleansing effects related to mental and physical relaxation. While it may sound odd to some Americans, the Japanese believe that simply being in a forest produces health benefits.
Activate your natural killer cells
Among the documented benefits are increased natural killer cell activity (these cells induce tumor cell death) and increased proportions of natural killer and T cells and proteins (all of which have anti-cancer activity). In one study, twelve apparently healthy men (mean age 43 years) spent three nights and two days in two forests. A variety of samples and measurements were taken from the subjects including blood samples, a Profile of Mood States questionnaire, activity using a pedometer, and sleep during a typical day at work before the forest visit and during and immediately following the forest visit. Eleven of the twelve subjects showed higher natural killer cell activity after the forest visit compared to during work. Forest bathing also increased the number of natural killer cells, as well as the number of other anti-cancer cells and proteins. These results suggest that frequent visits to a forest might reduce your risk of cancer.
Physiological and psychological benefits
A recent study supports the proposition that being in a forest promotes relaxation as evidenced by psychological and physiological changes. The study involved male undergraduate students at a Japanese university at 24 areas in Japan. In each area, 12 subjects with no reported history of physical or psychiatric disorders spent time sitting (about 14 minutes) and walking (about 16 minutes) in a forest (during one day) or in an urban environment (during an adjacent day). The subjects completed a Profile of Mood States Survey that assessed six dimensions of mood: tension / anxiety; depression / dejection; anger / hostility; fatigue; confusion; and vigor. Cortisol levels were analyzed from saliva samples. Heart rate variability and R-cardiac waves were measured with a portable electrocardiograph. Pulse and blood pressure were measured using oscilloscometric methods.
The researchers found that all six measures of mood before and after forest viewing or walking changed in the favorable direction (for example, less tension / anxiety) compared to urban viewing or walking. Similarly, salivary cortisol (a measure of stress), pulse rate, systolic and diastolic blood pressure, and the ratio of sympathetic to parasympathetic nervous system activity (a lower ratio indicates less stress) were significantly lower in after forest viewing or walking compared to urban viewing or walking.
This study supports other studies of shinrin-yoku as well as studies of human responses to forest environments relative to urban environments in other countries. All of the studies support the idea that forest environments reduce stress (for example, reduced cortisol, lower pulse) apparently by promoting relaxation. People who live in close proximity to forests have an opportunity to spend time in those forests by taking in the sights, sounds, and smells while sitting or walking. It’s tempting to speculate that exercising in a forest would provide addition benefits beyond those that would accrue from exercising in town.
Research in Taiwan showed that two hours of forest bathing in a nature education area promoted positive autonomic nervous system activity and emotions. The study include 128 middle-aged subjects (average age 60 years). More specifically, pulse rate, systolic and diastolic blood pressure, and anxiety all declined, while positive mood improved, after forest bathing.
Adults with hypertension benefit from forest bathing
Forest bathing appears to promote several aspects of better health including reduced psychological stress and better immune function. Forests emit volatile organic compounds that may benefit human health. Would older people with hypertension benefit from forest bathing? Researchers in China recruited 34 men and women (average 73 years) for a randomized trial to find out. Participants engaged in four activities (8 trigrams boxing, walking, tea ceremony, medication) either in a broad-leaf subtropical forest or in a large, busy urban area over a three-day period. Blood samples and psychological data were collected before and after the activities were completed. Compared to participants in the urban group, participants in forest bathing group showed significantly lower systolic, diastolic blood pressure, and high-sensitivity C-reactive protein (a measure of chronic inflammation) as well as greater heart-rate variability. These beneficial results suggest that regular periods of forest bathing might help resolve hypertension.
Would forest bathing help people with chronic obstructive pulmonary disease?
Chronic obstructive pulmonary disease (COPD) refers to persistent damage to the lungs that results in inflammation. Common manifestations include difficulty breathing, wheezing, and coughing up phlegm. COPD includes emphysema and chronic bronchitis. Researchers in Japan tested whether forest bathing would improve inflammatory markers associated with COPD and otherwise improve quality of life for patients at high risk of COPD. The study included 30 Japanese men with an average age of 63 years who scored high risk on a COPD screening questionnaire.
On the first day of the study day, all participants were driven to a hotel and ate the same meals. On the second day, the participants were randomized to one of 2 groups: forest bathing (walking 1.5 hours in the Akasawa Natural Recreation Forest) or urban walking (walking 1.5 hours in Ina City). On the third day, both groups switched group assignments. Both walking days featured fine weather. On the second and third days before and after walking, participants contributed blood samples (to analyze biomarkers), had their oxygen saturation measured, and answered questionnaires about their sleep, anxiety, fatigue, physical activity, and other aspects of physical and mental health.
After forest bathing, participants showed significantly improved levels of fibrinogen, C-reactive protein, interlukin-6, oxygen saturation, respiratory symptoms, and 4 out of 5 measures of subjective sleep quality, all of which denote better lung function compared to before forest walking. Forest walking induced significantly better levels of 6 of 8 measures of mood states and less fatigue. Both forest and urban walking significantly improved levels of fibrinogen, but only forest walking improved levels of 4 or 8 measures of mood states. In addition, compared to urban walking, forest bathing led to significantly better levels of interlukin-6, oxygen saturation, vigor and activity, and fatigue.
What might account for the positive effects of forest bathing? The answer might be better air quality in forests and the presence of chemicals (phytoncides), which are emitted by coniferous trees (such as cypress trees that live in the Akasawa Natural Recreation Forest). Researchers found phytoncides in the forest but not in the urban area. The air pollutants benzene, toluene, acetone, and xylene were present in the urban areas but not in the forest. Those of us who live in urban areas might do well to walk in nearby forests.
What to do
Those of us who live near forests can frequently spend time in those forests. Forest walking can provide two health benefits: greater physical activity and relief from daily stressors.
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]]>The post Hearing Loss, Dementia, and Quality of Life appeared first on Alan T. Carpenter.
]]>The 2024 update of the Lancet Commission report on dementia affirmed validity of the 2020 Lancet Commission report regarding 12 potentially modifiable risk factors for dementia and added new 2 new ones. In addition, the 2024 Commission report estimated the percentage of dementia cases attributable to each factor. Less education is the only early life factor that accounts for at least 5 percent of dementia cases. For mid-life, the 10 risk factors and the percentage of dementia cases attributable to each factor include: hearing loss (7 percent), high LDL-cholesterol (7 percent), depression (3 percent), traumatic brain injury (3 percent), physical inactivity (2 percent), smoking (2 percent), diabetes (2 percent), hypertension (2 percent), obesity (1 percent) and excessive alcohol consumption (1 percent). For late-life, the top three risk factors include social isolation (5 percent), air pollution (3 percent) and untreated vision loss (2 percent). Collectively, the 14 factors account for 45 percent of dementia cases. The most accessible and cost-effective dementia-avoiding actions for older Americans involve resolving any hearing loss (perhaps with hearing aids) and resolving any untreated vision loss (perhaps with glasses).
More evidence for benefits of resolving hearing loss
A new narrative review of dementia prevention and treatment noted the lack of compelling evidence from randomized controlled trials that interventions could prevent any type of dementia. On the positive side, older adults who address their hearing loss, keep learning, avoid smoking, cultivate social connections, and wear helmets while cycling will likely enjoy lower risk of dementia as well as other health benefits. Drugs designed to prevent or treat dementia have enjoyed little success. At this point, you best bet to avoid dementia is to embrace healthy lifestyle choices and hope for the best.
Hearing rehabilitation improves quality of life
Poor social networks predict increased risk of dementia. Researchers at UCLA conducted a systematic review and meta-analysis of 65 studies to better understand how hearing rehabilitation devices can improve social outcomes. Such devices included traditional hearing aids, cochlear implants, bone conduction hearing aids, and personal sound amplification. The average study participant had 64 birthdays. The 35 studies included in the meta-analysis showed that hearing rehabilitation use predicted a significant 22 percent improvement in quality of life. Cochlear implants produced double the quality of life improvement than traditional hearing aids. Meta-analysis showed that both cochlear implants and hearing aids predicted better social quality of life compared to baseline or control groups. As might be expected, longer use of hearing rehabilitation devices led to greater improvement in quality of life. Meta-analysis of 7 studies showed that hearing rehabilitation devices led to significantly lower perception of a social handicap due to poor hearing. Meta-analysis of 3 studies showed that use of a hearing rehabilitation device led to significantly lower loneliness. If you have difficulty hearing, why not get your hearing checked? If you have a hearing problem, why not do something about it to improve your quality of life?
You might not know that you have hearing loss
In 2024, the Lancet Commission identified hearing loss as the biggest modifiable risk factor for dementia. A new study investigated links between hearing loss, brain structural changes, cognitive function, and dementia. Data came from two samples of 1,656 and 935 participants on the Framingham Heart Study Offspring Study. Average ages of the samples of participants were 58 and 68 years, respectively. Hearing loss was measured by an audiologist. Compared to participants with no or slight hearing loss, participants with mild or greater hearing loss had significantly smaller brain volumes, larger white matter hyperintensivity volumes (a measure of neuron damage), and greater risk of developing dementia over 15 years of follow-up. These adverse outcomes doubled for participants with at least one APOE e4 gene. Interestingly, participants with slight or mild hearing loss often appeared to be unaware of it. On a positive note, participants with slight or more severe hearing loss had significantly elevated dementia risk, while participants with slight or more severe hearing loss who used hearing aids had a smaller, non-significant elevated risk. Older people might benefit from having their hearing tested. If the evaluation finds hearing loss, a hearing aid can maintain better quality of life and reduce risk of dementia.
More evidence that hearing aids reduce risk of dementia
Would persons who use a hearing aid reduce their risk of dementia? Researchers used data from 2,953 participants with an average baseline age of 69 years in the Framingham Heart Study (both the original and the offspring cohorts) to find out. Compared to participants under age 70 with clinically measured hearing loss without hearing aid, participants under age 70 with clinically measured hearing loss with hearing aid had a significant 61 percent lower risk of developing dementia during 20 years of follow-up. Compared to participants under age 70 with hearing loss and no hearing aid, participants under age 70 with no hearing loss (no need for a hearing aid), had a 27 percent lower risk of developing dementia. The dementia risk for participants with hearing aid use did not change significantly for participants over age 70 years. If you have yet to reach age 70 and think you might have hearing loss, you might get your hearing checked. Alas, only 17 percent of persons with moderate to severe hearing loss use hearing aids.
What to do
Given the huge downsides of developing dementia, wouldn’t it make sense to get your hearing checked if you think you might have hearing loss? Plus, life will be more enjoyable when you can hear better. If you’re on Medicare, check to see if your Part B Supplemental or Medicare Advantage insurance covers hearing tests and hearing aids.
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]]>The post Exercise, Diet, and Cancer Treatment appeared first on Alan T. Carpenter.
]]>Prostate cancer patients often take androgen-deprivation drugs to slow the rate of cancer progression. However, such drugs have side-effects including increased levels of fatigue and lower quality of life. Exercise can reduce fatigue but which exercise regimes reduce fatigue the most was previously unknown. Researchers in Australia conducted a year-long randomized controlled trial to determine which of three exercise interventions would best diminish fatigue and increase vitality of prostate cancer patients. The exercise programs included 1) impact loading and resistance training (ILRT), 2) aerobic and resistance training (ART), and 3) usual care supplemented with information about the health benefits of exercise for six months followed by six months of delayed aerobic and flexibility exercise (DEL). Participants included 163 men with an average of 69 years with diagnosed prostate cancer and undergoing androgen-deprivation therapy. Supervised twice-weekly exercise sessions included a variety of movements that differed across the groups.
Fatigue significantly declined and vitality significantly increased in all three groups at 12 months with no significant differences among the groups. Both cardiovascular fitness and muscle strength increased significantly for ILRT and ART but only marginally for DEL. Patients with the highest levels of fatigue at baseline showed the greatest benefit from the exercise programs. Thus, prostate cancer patients undergoing androgen-depriving therapy may experience less fatigue and better quality of life by increasing their levels of exercise.
Prostate cancer treatment and bone mineral density
The list of adverse effects of androgen-depriving drug drugs for prostate cancer patients also includes diminished bone mineral density (BMD). Reduced BMD increases risks of osteoporosis and fractures. Bisphosphonates are widely prescribed to increase BMD but have their own serious drawbacks. Researchers in Australia also conducted a year-long randomized controlled trial to determine the ability of the same three exercise interventions to preserve or increase BMD. Participants in this study included 154 men with an average of 69 years with diagnosed prostate cancer and undergoing androgen-deprivation therapy. After one year, BMD at the lumbar spine and femoral neck and declined significantly by 0.5 to 3.0 percent in all three interventions. The ILRT group experienced the least amount of decline at both lumbar spine and femoral neck (0.5 and 2.0 percent, respectively). This study suggests that impact exercise, such as jumping, hopping, and leaping, slowed the decline in BMD more than aerobic or general exercise.
Exercise programs work for cancer patients
A recent review documented the benefits of combining exercise, particularly resistance training, with cancer treatment. Resistance exercise leads to increased muscle mass and strength, along with improved balance, mobility, and body composition, plus lower risk of falls. Ideally, resistance training would feature individualized, high-intensity movements align with normal mobility patterns and are suitable for the patient. Training should occur 2 or 3 times per week with sessions lasting up to an hour. An exercise specialist should develop a plan in consultation with the patient and supervise the exercise sessions, at least initially, to make sure the patient uses correct form. Evidence supports the idea that cancer survivors who follow a structured, supervised exercise plan can participate in resistance training and build muscle mass and strength, balance, mobility, and improve body composition with minimal risk of injury.
Cancer doctors weigh in on exercise and diet
Persons with obesity have elevated risks of cancer and other adverse health outcomes. The proven ability of GLP-1 inhibitors to induce substantial weight loss has prompted the medical establishment to recommend weight-loss drugs to accompany cancer treatment for patients with obesity. However, GLP-1 inhibitors can lead substantial loss of muscle mass, which increases risks of sarcopenia, frailty, falls, and mobility disability. Thus, solving one problem (reducing obesity) may lead to other problems. A trio of cancer doctors urges their colleagues to favor a different approach: increased physical activity, especially resistance training, and better diet, both of which effectively maintain muscle mass over time. The drawback of this approach lies in the reluctance of most patients to boost their physical activity and eat better as a new way of living. Thus, these doctors urge that GLP-1 inhibitors should be prescribed only when prescriptions to increase physical activity and improve diet have failed.
Surviving colon cancer with exercise
A new randomized trial confirmed previous studies that found that structured exercise following cancer treatment increased patient survival. The new trial included 889 patients with an average baseline age of 61 years at 55 medical centers mostly in Canada and Australia. All patients had finished their treatment following surgery to remove colon cancer within 2-6 months prior to the start of the trial. Patients were randomized into one of two groups. The health education group included materials that promoted physical activity and nutrition. The exercise group included the educational materials plus an exercise guidebook for cancer survivors and support from an exercise consultant for 3 years. The exercise program featured behavior-change techniques, supervised exercise sessions, and in-person or video support sessions. The goal of the exercise program was to increase progressively the amount of brisk walking over 3 years.
Adherence to the mandatory behavioral support sessions ranged from 83 percent during the first 6 months to 59 percent for the final 6 months. After a median follow-up of 7.9 years, patients in the exercise group had a significant 37 percent lower risk of dying compared to patients in the health education group. Exercise also significantly increased disease-free survival, thereby increasing quality of lifespan. Both groups increased their levels of physical activity, cardiorespiratory fitness and physical functioning over 3 years, although patients in the exercise program achieved much higher amounts of moderate to vigorous exercise than the patients in the health education program. Thus, simply providing information about the benefits of exercise and nutrition was less effective than providing information and long-term support.
Breast cancer, exercise, diet
Higher levels of body fat predict increased risk of breast cancer recurrence. Plus, women who gain weight during and after breast cancer treatment have increased risks of cancer recurrence, metastases, and death. Cancer researchers tested whether a 3-month, thrice-weekly program of progressive weight training coupled with a healthy low-carbohydrate diet would reduce body fat and increase muscle mass and strength in 44 breast cancer patients. Certified exercise specialists supervised the exercise sessions that used inexpensive free weights. The healthy low-carb diet mirrored the DIETFITS diet developed at Stanford University and included high amounts of fruits and colorful non-starchy vegetables and minimal amounts of sugar, refined carbohydrates, bread and pasta. Participants were also advised to eat at home with family as much as possible and avoid junk food.
In fact, the program accomplished its objectives. Over 3 months, body fat significantly decreased by 4 lbs., while muscle mass significantly increased by 1 lb. In addition, patients significantly improved three measures of quality of life. The researchers attributed the program’s success to its emphasis on encouraging participants to push themselves to lift higher loads to increase muscle mass and reduce fat mass without increased risk of injury in a closely supervised setting.
What to do
If you or someone you know is undergoing cancer treatment, you might mention to this person that more exercise and a better diet might help him or her life better and longer through the rigors of treatment.
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]]>Researchers in Denmark conducted a study testing the effects of four weight-loss strategies for persons with obesity, without diabetes, and with an average age of 42 years. The four strategies included 1) the GLP-1 drug liraglutide (Saxenda) plus usual activity, 2) liraglutide plus exercise, 3) placebo plus exercise, and 4) placebo plus usual activity. The main outcome was change in body weight. The four strategies followed an 8-week, low-calorie diet in which all participants consumed an 800-calorie meal replacement drink as their only daily food. At the end of 8 weeks, the average participant lost 13.1 kg (29 lbs) of body weight.
During the following 12 months, participants could meet individually with a dietician to support weight loss maintenance. During those 12 months, the liraglutide plus exercise group outperformed the other groups with an additional loss of 3.4 kg (7 lbs) of body weight. Members of the liraglutide plus exercise group also showed greater gains in cardiorespiratory fitness, insulin sensitivity, and general health perception than the other groups. While lean mass declined by about 5 kg (11 pounds) during the 8-week weight-loss period, participants in the liraglutide plus exercise group regained all of the lost lean mass and then some. The combination of liraglutide plus exercise led to substantial weight loss, no weight regain, and no loss of lean mass.
A more recent example of dramatic weight loss
Researchers at a medical center in France conducted a weight loss study using the GLP-1 agonist drug semaglutide (Wegovy). The 12-month study included 115 patients with an average age of 52 years and with grade 3 obesity (body mass index of 40 or more) and with at least one related comorbidity, such as obstructive sleep apnea. Patients at 7 and 12 months post-baseline lost 9.8 and 18.9 percent of their baseline body weight. Fat mass declined by 14 and 18 percent from baseline to 7 and 12 months, respectively. Fifty-nine percent of the patients lost 10 percent or more of their baseline body weight. From baseline to 7 months, lean mass (non-fat body mass) decline significantly by 3.0 kg (6.6 lbs), but it stabilized by 12 months. Handgrip strength increased significantly at 7 months by 3.4 kg and increased further to 4.1 kg at 12 months. The proportion of patients with sarcopenic obesity declined from 49 percent at baseline to 33 percent at 12 months. Curiously, the authors concluded that lean mass was preserved, even though it declined significantly.
Even more dramatic weight loss
GLP-1 receptor agonist drugs and the combination of a GLP-1 receptor drug and a glucagon-dependent insulinotropic polypeptide receptor agonist drug (got that?) produce major loss in body weight, especially body fat. These drugs can also induce substantial and disconcerting loss in lean mass and muscle mass. However, studies report wide variations in loss of body fat and lean mass. Part of the variation may arise from measurement-related errors. Most weight loss studies measure lean mass with DEXA (more available, relatively inexpensive, less time-consuming to use) but do not measure muscle mass with MRI (less available, relatively expensive, more time-consuming to use). Loss of lean mass (often measured in weight loss trials) does not equal loss of muscle mass, because lean mass includes non-muscle items, such as organs, bone, and water. Results of studies using MRI suggest that loss of muscle volume aligns with that which is expected considering patient age, sex, comorbid conditions, and the amount of weight loss.
Further complicating the situation, these weight loss drugs can improve insulin sensitivity and reduce fat infiltration into muscle cells, thereby improving muscle quality. In addition, combining new weight loss drugs with increased physical activity (aerobic, strength training) and increased protein intake may limit muscle loss. Older patients with obesity and at risk for sarcopenia (generalized muscle wasting) and with comorbid conditions need to carefully consider using GLP-1 drugs for weight loss.
Concerns about older people losing muscle mass, sarcopenia
The glucagon-like peptide 1 receptor (GLP-1) agonist drugs liraglutide and semaglutide produce major loss of body mass in adults with overweight and obesity. Fat accounts for most of the body mass loss, but lean mass can also account for a sizeable fraction. Loss of about 6 kg (13 lbs) of lean mass in some trials corresponds to a decade or more of aging. Newer weight-loss drugs that also contain glucose-dependent insulinotropic polypeptide (GIP) receptor agonists (tirzepatide), and also glucagon receptor triple agonist (retatrutide) appear to induce even more loss of body fat and potentially lean mass. Lean mass includes muscle, bones, and connective tissue.
Older people who lose muscle mass may also lose strength, both of which predict increased risk of cardiovascular disease, sarcopenia, frailty, and death. Thus, loss of lean mass arising from weight-loss drugs may negate some of the drugs’ positive effects. On the positive side, long-term resistance training leads to increased lean mass and strength. The combination of semaglutide or liraglutide and resistance training could lead to substantial loss of fat mass, while limiting the loss of lean mass. Furthermore, retaining lean mass could limit the amount of weight regain after a weight-loss drug is terminated.
Strategic use of GLP-1 receptor agonist drugs
While GLP-1 agonist drugs are changing the face of weight loss, potential down sides merit close attention. A trio of researchers argue that weight loss using GLP-1 agonist drugs needs to consider potential muscle mass and muscle strength loss, along with increased risk of sarcopenia. In addition, muscle plays key roles in numerous metabolic processes that extend beyond strength, balance, posture, and movement. The researchers state that weight loss with GLP-1 agonist drugs must be used strategically with concurrent exercise and nutrition components. Regulatory agencies need to provide more comprehensive guidance for researchers to evaluate body composition using appropriate technology.
Benefits of skeletal muscle measurement
Researchers in Canada reviewed the importance of skeletal muscle in weight loss in persons with obesity. High-quality weight loss features a high proportion of fat loss and a low proportion of skeletal muscle loss. Skeletal muscle affects a range of bodily processes and states including glucose metabolism, metabolic flexibility, mobility, and strength. Loss of muscle mass leads to reduced basal metabolism, which promotes weight gain. In addition, greater muscle mass promotes greater insulin sensitivity, better blood sugar management, and greater glucose metabolism. More muscle mass also provides a wider pathway for blood sugar metabolism. Exercise leads to maintained or increased muscle mass and reduced fat inside muscle cells. Alas, measuring skeletal muscle accurately requires expensive equipment (MRI or CT) and considerable time. On top of that, researchers sometimes conflate muscle-related terms, such as lean mass and muscle mass, which are not the same.
Research suggests that patients undergoing weight loss need to take steps to reduce their risk of skeletal muscle loss. One step is to engage in a regular program of strength training. While the details vary among individuals, a typical program might include working out at a gym two or three times per week for an hour each time performing resistance exercises with weights and/or weight machines. Another step, especially for those doing weight training, is to increase daily protein intake above the standard recommendation of 0.8 grams of protein per kg of body weight by 50 percent to about 1.2 grams of protein per kg of body weight. This translates into 82 grams of protein per day, ideally consumed in three relatively equal portions, for a 150 pound person. Overall, persons undergoing rapid weight loss can improve their health and well-being by engaging in resistance training and eating enough protein.
More concerns
A new mini-review cautions that GLP-1 drugs may lead to substantial muscle loss along with substantial weight loss. In addition, cessation of GLP-1 drugs may lead to hefty weight regain (mostly fat), with little or no muscle regain. Weight cycling, arising from periods of GLP-1 drugs commencing then stopping may lead to sarcopenic obesity, an unhealthy combination of excess body fat and substandard muscle strength and/or function.
Exercise and adequate nutrition can limit downside risk of GLP-1 drugs
The burgeoning use of GLP-1 drugs to reduce obesity rapidly can induce unfavorable side-effects including loss of skeletal muscle mass and function. Recent evidence suggests that treatment of obesity with these drugs over 68-72 weeks can lead to 10 percent loss of muscle, equivalent to 20 years of age-related muscle loss. Two key factors, adequate nutrition, especially protein intake, and adequate physical activity, especially resistance training, can limit muscle loss during rapid weight loss. All patients using GLP-1 drugs for weight loss should participate in programs that promote adequate nutrition and physical activity.
What to do
If you’re contemplating asking your doctor to prescribe a GLP-1 drug so you can lose a lot of weight, make sure that you understand the potential risks and rewards. Are you willing to reduce your risk of muscle loss by participating in exercise training and increasing your protein intake?
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]]>Determining the healthfulness of foods isn’t easy, even after reading food labels. Yet, many people want to eat healthy foods. Researchers at Tufts University developed and validated a nutrient profiling system, Food Compass. This system scores 54 attributes across nine health-relevant domains: nutrient ratios, vitamins, minerals, food ingredients, additives, processing, fats, fiber and protein, and phytochemicals. The summed domain scores yields a Food Compass Score (FCS) ranging from 1 (least healthy) to 100 (most healthy) for a wide variety of foods and beverages. For example, savory snacks and sweet deserts had an average FCS of 16, while legumes (beans, lentils) had an average score of 79. Examples of foods with scores of 90 or above include vegetable curry, seafood, garden salad, plain nonfat Greek yogurt, salmon, a dozen different fruits, many vegetables, Cheerios, tomato juice, and celery juice. The FCS distinguished between certain foods and beverages better than other nutrient profiling approaches, such as NOVA, Health Star Rating, and Nutri-Score.
Validation of Food Compass for Health Measures
Researchers at Tufts then validated the utility of an individual person’s Food Compass Score (iFCS) with data from 47,999 participants in the National Health and Nutrition Examination Surveys against the Healthy Eating Index (2015), clinical risk factors, and all-cause mortality. The average iFCS score of 35.5 signified a generally unhealthy diet. iFCS values correlated strongly with the Healthy Eating Index (2015). Each one standard deviation increase in iFCS score (10.9 points) predicted more favorable body mass index (-0.6 unit), systolic and diastolic blood pressure (-0.91 and -0.49 mm Hg), LDL-cholesterol (-2.01 mg/L), HDL-cholesterol (1.65 mg/dL), HbA1c (-0.02 percent), and blood plasma glucose (-0.44 mg/dL). Each one standard deviation increase in iFCS score also predicted lower odds of the metabolic syndrome (15 percent lower), cardiovascular disease (12 percent lower), cancer (5 percent lower), lung disease (8 percent lower), and mortality (11 percent lower). Age, sex, education and BMI minimally affected iFCS scores. Thus, the Food Compass may be a useful tool to encourage healthy eating.
Food Compass 2.0
Researchers at Tufts University developed the Food Compass nutrient profiling system in 2021. The system assessed the healthfulness of over 9,000 different foods (including mixtures of foods) in nine domains on a scale from 1 (most unhealthy) to 100 (most healthy). In 2024, Tufts researchers published Food Compass 2.0, an update of the original Food Compass system to reflect more recent scientific health-diet data. Food Compass 2.0 scores for certain food groups, such as nuts, legumes, and sauces/condiments, were similar to the original Food Compass scores. However, Food Compass 2.0 scores declined notably for other food groups, including cold cereals, plant-based dairy, cereal bars, and fruit and vegetable juices. At the same time, Food Compass Scores increased notably for other food groups, including beef, seafood, lamb and game, eggs, and rice/pasta. Of 44 categories of foods, the top five healthiest, according to both Food Compass and Food Compass 2.0, included green vegetables, berries, citrus, nuts and seeds, and other vegetables. The five unhealthiest foods included cured meats, dairy animal fats, desserts, sweet drinks, and bread. The obvious lesson: Emphasize the healthiest foods and de-emphasize the unhealthiest ones.
Food Compass Score-10
One drawback of Food Compass is the requirement for nutrition information that may not be widely available. Researchers at Tufts University developed and validated the Food Compass Score-10 using data commonly available on foods packages to rectify this shortcoming. Food Compass Score-10 is scaled from 1-10 with 1 denoting the unhealthiest and 10 denoting the healthiest foods. In addition, Food Compass Score-10 scores were categorized as follows: 1) foods to encourage (scores of 7 or higher), 2) foods to consume in moderation (scores of 4-6), and 3) foods to limit (scores of 3 or lower). The Food Compass Score-10 scores correlated strongly with the Food Compass scores. In addition, Food Compass Score-10 placed foods in the three categories similar to Food Compass. Compared to Food Compass, Food Compass Score-10 provides an easier way to identify the healthfulness of packaged foods, while maintaining the structure of the Food Compass system.
Do food labels induce shoppers to purchase healthier foods?
In 2025, the US Food and Drug Administration (FDA) finalized the rules for front-of-package labeling. The Nutrition Info label includes the percentages of recommended daily values for saturated fat, sodium, and added sugar on a per serving basis, and either a low (most healthy), medium or high (least healthy) rating for each. Researchers at Tufts and elsewhere conducted a randomized clinical trial to compare the purchases of packaged snack foods with respect to no label, the proposed FDA label and the Food Compass label. The study included 275 shoppers with a median age of 55 years at 6 locations of 3 supermarket chains in Massachusetts. Compared to no label, both the FDA and Food Compass label significantly increased the purchases of healthier snack foods (11.2 vs. 6.4 percent). Compared to no label, both the FDA label and the Food Compass label significantly reduced the purchases of unhealthy snack foods (-7.2 vs. -6.3 percent). The Food Compass label (but not the FDA label) significantly increased the odds of no snack food purchase by 4.0 percent (which might alarm food retailers). Both labels accomplished the intended objectives of increasing purchases of healthier snack foods and reducing the purchases of unhealthier snack foods.
What to do
It’s worth your while to take a few seconds when you make a food purchase to gauge its healthiness. At present, you pretty much have to rely on back-of-package N utrition Facts. From what I could learn online, the FDA label won’t appear anytime soon. In addition, food manufacturers and retailers are developing their own nutrient profiling systems. You would be well-served to eat more of the foods that Food Compass identified as the healthiest, namely green vegetables, berries, citrus, nuts and seeds, and vegetables generally.
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]]>The post Meal Timing Updated appeared first on Alan T. Carpenter.
]]>In 2019, I wrote a blog post about skipping breakfast. A review of clinical trials found that breakfasts that contained larger amounts of protein (30 grams of more), more energy (more than 350 calories), and which consisted of solid foods (as opposed to liquids) led to greater appetite control and satiety compared to breakfast skipping.
A systematic review and meta-analysis of 13 trials found that skipping breakfast predicted a small but significant reduction in weight (0.44 kg) compared to eating breakfast. However, of the included studies, I saw only one breakfast that I would consider “healthy.” Common breakfast items included packaged cereal, milk, and juice. In my view, these breakfasts included insufficient protein, fiber, fat, and calories. This meta-analysis compared the effects of eating a lousy breakfast or skipping it.
Physical activity after breakfast
A more recent study by British researchers investigated whether the timing of physical activity with respect to breakfast consumption affected post-meal interstitial glucose concentration (measured with a continuous glucose monitor). Forty-eight generally healthy, physically active adults were randomly assigned to one of three physical activity conditions: standing, walking, and circuit training, each for 30 minutes. Within each activity condition, participants completed four trials in random order. For Trial A, participants fasted overnight, arrived at the laboratory at 8 am, and immediately consumed a 500-calorie meal-replacement breakfast. After glucose was measured at 2 hours post-breakfast, the participants left the lab and completed their physical activity at some point later in the day. Trial B mirrored Trial A except that participants began their physical activity at 8am and consumed breakfast 30 minutes later. Trial C also mirrored Trial A except that participants completed their physical activity immediately after they ate breakfast at 8 am. Trial D was identical to Trial C except that participants completed their physical activity starting 30 minutes after eating breakfast.
Compared to Trial A (the non-active control condition), participants in Trial C (immediate post-meal physical activity) had significantly lower average glucose and lower total glucose over 2 hours post-meal regardless of the type of physical activity. Thus, 30 minutes of light- to moderate-intensity physical activity immediately following breakfast reduced the post-meal glucose spike and reduced glucose for 2 hours. After you finish your daily meals, can you find a way to move around for 30 minutes? How about a 30-minute after-meal walk following your biggest meal? If so, over time, you may reduce your risk of type 2 diabetes.
Late-evening snacking
Recent studies propose that the time of day you eat affects how your body processed the food you eat. Researchers at Vanderbilt University utilized data from six participants who spent two 56 hour periods in a whole-room respiratory chamber (except for two, 20-minute breaks) to test this idea. Fun, huh?! Instruments measured the changes in oxygen and carbon dioxide in the chamber arising from a participant’s metabolism. During one period, each participant ate dinner, and ate breakfast, lunch, and dinner over the following two days. During the other period, each participant ate dinner followed by a snack four hours later and ate lunch and dinner (but no breakfast) the following two days. The breakfast and the snack were nutritionally equivalent. The interesting finding: Eating a 700-calorie after-dinner snack about 7:45 pm dampened the body’s ability to metabolize fats compared to eating the equivalent amount and type of food at breakfast. Thus, eating breakfast, lunch, and dinner then avoiding after-dinner snacking might help people with overweight or obesity reduce their body fat.
Meal timing matters
Insulin sensitivity and blood sugar tolerance change during the day in response to circadian rhythms, with the optimal metabolic time occurring in early morning. Researchers in Europe used data from 103,312 participants with an average of 43 years in the NutriNet-Sante cohort to determine if meal timing predicted the risk of type 2 diabetes. After adjusting for confounding factors and compared to participants who reported eating their first meal of the day before 8 am, those who reported eating their first meal of the day after 9 am had a significant 62 percent higher risk of developing type 2 diabetes during a median follow-up of 7.3 years. Also, participants who ate dinner before 7 pm and who ate breakfast the next day before 8 am (equivalent to a 13-hour overnight fast) had a 53 percent lower risk of developing diabetes compared to other participants. Combining an early dinner with an early breakfast the next day might help manage blood sugar and maintain insulin sensitivity, thereby reducing the risk of type 2 diabetes.
More on meal timing
The timing and amount of food consumption relative to daily circadian rhythms appears to affect several measures of health. A recent review arrived at the following tentative conclusions. 1) Skipping breakfast may increase coronary heart disease, type 2 diabetes, hypertension, and obesity risk factors. 2) Eating breakfast earlier rather than later may reduce odds of the metabolic syndrome. 3) Eating lunch earlier may lead to better blood sugar control and lower insulin resistance. 4) Eating dinner later and eating more calories at dinner may increase risk of cardiovascular disease and the metabolic syndrome. 5) Increased day-to-day variability of the timing of breakfast and dinner may lead to higher body mass index, blood sugar, and inflammation.
Based on these findings, here’s an approach to healthy meal timing and amount. Eat a substantial breakfast at 7 am after arising, eat a more substantial lunch (the biggest meal of the day) at noon, and eat a modest dinner (the smallest meal of the day) at 5:30 pm. No food after dinner until breakfast. Alas, I have to figure out how to stop eating after dinner,
Breakfast suggestion
I recommend eating breakfast, but make it one that’s worth eating with quality foods that provide sufficient protein, fiber, and calories. My typical breakfast starts with a banana, then steamed veggies (either zucchini, or cauliflower, or broccoli) followed by a bowl of oatmeal made with a half cup of thick rolled oats and a quarter cup of wheat bran. I top the cooked oatmeal with half a cup of soy milk, ¼ cup of whey protein, a half cup of plain, lowfat Greek yogurt, a half-cup of fruit (either peaches, or pears, or frozen blueberries), and a dash of cinnamon.
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