Limit carbohydrate intake
Keep your blood glucose in a healthy range
The medical establishment has long advocated a low-fat diet to reduce the risk of type 2 diabetes. Yet, accumulating evidence supports limiting carbohydrate intake leads to equal or better results. Researchers at the University of Connecticut tested the idea that the biological markers of carbohydrate-restricted diets align with those of the metabolic syndrome. Forty overweight persons with an average age of 35 years were randomized to either a low-carbohydrate or a low-fat diet for 12 weeks. Participants in both diet groups received weekly guidance from dieticians regarding foods, meal plans, and other ways to maintain fidelity to their assigned diet.
Both groups spontaneously reduced caloric intake by about 25 percent although they were not advised to do so. Carbohydrate intake by both groups dropped significantly but much more so for the low-carb diet group. Body mass, fat mass, and abdominal fat mass all declined in both groups but more in the low-carb group. Blood glucose, insulin, total daily insulin, and HOMA (a marker of insulin resistance) all declined significantly more in the low-carb compared to the low-fat group. Similarly, triglyceride, HDL-cholesterol, triglyceride / HDL-cholesterol ratio all declined significantly more in the low-carb compared to the low-fat group. Finally, the ratio of small, dense LDL-cholesterol particles (more plaque forming) to large, buoyant LDL-cholesterol particles (less plaque forming) declined significantly in the low-carb group but not in the low-fat group. Overall, the low-carb diet group showed much healthier biomarkers of the metabolic syndrome than the low-fat group. Thus, consuming a low-carbohydrate diet may help you eat better and improve biochemical factors that predict lower risk of obesity, cardiovascular disease, and type 2 diabetes and better metabolic health.
Researchers at the University of California – San Francisco conducted a randomized trial to see if a very-low carb diet would lead to better metabolic health than a moderate-carbohydrate diet. The trial included two diets: 1) an ad libitum very-low-carbohydrate, likely ketogenic diet (target of 20-50 grams of daily carbohydrate exclusive of fiber), and 2) a calorie-restricted (target of reducing energy intake by 500 kcal/day) moderate-carb, reduced fat diet. After three months, the very low-carb diet led to better blood sugar control for diabetic or pre-diabetic participants. Would the promising three-month results of improved metabolic health continue to 12 months?
After 12 months, participants in the very low-carb group showed significantly lower concentrations of HbA1c (above 6.5 percent indicates diabetes), greater likelihood of discontinuing diabetes medications, lower body weight, and lower triglyceride/HDL-cholesterol ratio compared to the moderate-carb group. These results suggest that adults with type 2 diabetes or pre-diabetes might be able to improve their metabolic health related to type 2 diabetes, including remission from diabetes and/or reduced use of diabetes medication—without having to restrict total calories.
One-third of US adults have pre-diabetes, a condition with elevated blood sugar but not high enough to be diagnosed as type 2 diabetes. The National Diabetes Prevention Program (NDPP), developed by the Center for Disease Control (CDC), seeks to reduce the risk of type 2 diabetes via substantial body-weight loss. But low patient retention (30 percent) in NDPP programs and the difficulty of losing 5 percent of body weight over nine months (to qualify for full recognition by CDC and reimbursement from the Center for Medicare and Medicaid Services) has motivated researchers to develop a better approach to preventing diabetes.
To that end, a team of researchers recruited 96 type 2 pre-diabetic patients (average age 52 years) with obesity in the Lafayette, Indiana, area for a two-year continuous, remote care intervention. The purpose of the intervention was to normalize blood sugar levels and to prevent or postpone type 2 diabetes. The intervention involved a mobile, web-based app that connected patients to their remote care team. The team included a health coach who provided nutrition and behavior change support and a medical provider who monitored biomarkers and medications for diabetes and hypertension. The app also included access to educational resources and peer support. Participants could receive education sessions online or in person.
Patients were advised initially to restrict carbohydrates to 30 grams per day or less, consume 1.5 grams of protein per kg of body weight daily (for example, 102 grams protein daily for a 150-pound person), and eat fat to the point of satiety. If followed, this diet would produce a state of nutritional ketosis, as evidenced by blood beta-hydroxybutyrate levels of less than 0.5 mmol/L. Slightly more than half of the patients met the above nutritional ketosis goal. After two years, 75 percent of the patients were still enrolled. At two years and based on all 96 patients initially enrolled, 52 percent had normal blood sugar levels, 45 percent had pre-diabetes, and only 3 percent of the patients progressed to type 2 diabetes. Importantly, the prevalence of both the metabolic syndrome and fatty liver disease (closely linked to type 2 diabetes risk) declined to about half of the baseline values. This study suggests that the risk of type 2 diabetes (and the metabolic syndrome and fatty liver disease) can help you eat better with a very-low carbohydrate diet rather than focusing on weight loss.
Low-carbohydrate diets promote weight loss in patients with type 2 diabetes in short-term clinical trials. But are low-carb diets effective over the longer-term? The Vita Health Corp. in San Francisco collaborated with a local medical care provider and recruited patients aged 21 - 65 years with type 2 diabetes for a two-year study. Patients self-selected to receive the continuous care intervention (N=262) or usual care (N=87). The continuous care intervention (CCI) patients received a web-based software application that provided telemedicine communication, online resources, and biomarker tracking tools. Participants could use the app to upload and monitor their personal biomarker data (body weight, blood glucose, and beta-hydroxybutyrate, a marker of ketosis nutritional). Patients could select whether they wanted to receive virtual or personal education and health counseling. Patient retention in the study was high for both CCI (74 percent) and usual care (78 percent) groups.
From baseline to two years, seven measures of glycemic control improved for the CCI group compared to the usual care group. For example, HbA1c levels in the CCI group dropped by 0.9 percent but increased by 0.4 percent in the usual care group. In addition, fasting blood glucose levels in the CCI group dropped by 29 mg/L, but increased by 21 mg/L in the usual care group. Body weight of participants in the CCI group declined by 11.9 kg, while it increased by 1.3 kg in the usual care group. For measures of cardiovascular health, systolic and diastolic blood pressure improved more in CCI patients than in usual care patients. Total cholesterol and LDL-cholesterol both significantly increased in the CCI group but not in the usual care group. C-reactive protein, a measure of systemic inflammation, declined significantly in the CCI group but not in the usual care group. The proportion of participants taking diabetes medications declined significantly in the CCI group but increased significantly in the usual care group. The daily insulin dose declined significantly in the CCI group but didn’t change in the usual care group. Overall, patients in the CCI group improved multiple markers of diabetes and cardiometabolic health and used less medication after two years.
These and other studies suggest that you’ll enjoy better metabolic health if limit your intake of carbs, especially from starchy, sugary, and ultra-processed foods, and emphasize leafy and other green, red, and orange vegetables.