Ectopic Fat

What is ectopic fat?

This term refers to the accumulation of fat molecules (triglycerides) in organs not designed to store fat. More specifically, ectopic fat can occur in your liver, pancreas, heart and skeletal muscles with undesirable consequences. Until recently, adipose tissue, which is comprised of fat cells, was thought be solely a fat storage depot. Scientists have since learned that adipose tissue secretes a variety of hormones and cytokines that can adversely affect glucose and blood fat (lipid) metabolism and promote chronic inflammation. Metabolic dysfunction leads to ectopic fat deposition.

A group of Dutch researchers reviewed the evidence relating to ectopic fat and insulin resistance. Fat cells can expand dramatically in order to store more fat (in the form of triglyceride) under the skin, increasing their volume a thousand fold (this is not a typo). At some point, subcutaneous fat cells can't hold any more fat. Excess fatty acids end up in other tissues, including liver, pancreas, heart and skeletal muscles as ectopic fat. The presence of ectopic fat compromises the functions of these overflow fat depots. Ectopic fat in the liver and the pancreas is associated with insulin resistance and type 2 diabetes. On the positive side, a combination of steep caloric restriction and consequent substantial weight loss abetted by increased physical activity can rapidly and greatly reduce the abundance of ectopic fat.

Reducing visceral fat

Accumulating evidence suggest that excess visceral fat (in and around the abdomen) triggers a series of metabolic disturbances evidently related to ectopic fat stored in the liver, pancreas, heart, skeletal muscles. Thus, reducing visceral fat may reduce metabolic problems. A systematic review and meta-analysis of 15 trials evaluated effects of different exercise regimes of at least 8 weeks duration on visceral fat of persons with overweight or obesity. Overall, exercise led to a significant decrease in visceral fat. The effect of aerobic exercise proved to be the most effective, while the effects of strength training or combined aerobic and strength training were not significant. Moderate and high-intensity training predicted lower visceral fat, while light-intensity training did not. These positive outcomes occurred without caloric restrictions. A program of moderate- or high-intensity aerobic training can reduce visceral fat for persons with overweight or obesity and may reduce their risk of cardiovascular disease and type 2 diabetes

Added sugar and lots of calories may build ectopic fat

Over the past few decades, we Americans have greatly increased our consumption of added sugars and increased our body weight and body fat. Would eating and drinking more sugar increase our risk of ectopic fat? Researchers in Boston conducted a systematic review of relevant published studies to find out. A meta-analysis of 14 studies showed that compared to controls with the same caloric intake, participants who consumed added sugar while also consuming excess calories were significantly more likely to have ectopic fat, especially in the liver and in skeletal muscles.

Regular aerobic exercise

Excess body fat, especially visceral fat that surrounds the internal organs, predicts higher risk of cardiovascular disease and type 2 diabetes. Small amounts of ectopic fat that permeate the liver, pancreas, heart, and skeletal muscles lead to increased insulin resistance (the inability of insulin to escort blood sugar into muscle cells), higher blood insulin and blood sugar concentrations, and increased risk of type 2 diabetes. Key lifestyle changes that help prevent diabetes and cardiovascular disease include Keep Moving and Eat Better.

An older systematic review and meta-analysis found that regular exercise may decrease visceral and liver fat and improve cardiovascular health. A more recent systematic review and meta-analysis included 24 studies that used aerobic exercise or progressive resistance exercise to reduce visceral and liver fat of adults with type 2 diabetes. Pooled data from 13 of these studies showed that moderate to vigorous exercise predicted significantly reduced visceral fat, even though none of the individual studies showed significant decreases. (Pooling data increases sample size and statistical power and increases the likelihood of finding significant effects.) Data pooled from four studies showed a barely non-significant exercise-induced reduction of liver fat. Sub-analyses showed that aerobic exercise but not progressive resistance training or a combination of resistance and resistance training predicted less visceral fat. In addition, aerobic exercise led to less significantly less visceral fat even without body weight loss. This good news story showed that moderate or vigorous aerobic exercise conducted several times a week may reduce visceral fat, insulin resistance, and blood sugar, thereby lessening the risk of or possibly reversing type 2 diabetes—even without overall body weight loss

Shrink the beer belly

Several decades of research show that visceral fat (within the abdomen) predicts increased risk of dying from cardiovascular and metabolic diseases, such as type 2 diabetes. Recent research suggests that ectopic fat deposited in the liver and heart muscle may also increase atherosclerosis and cardiometabolic risk. Interestingly, the widely used body-mass index (BMI) does not adequately predict health risk, because BMI does not distinguish visceral and ectopic fat from subcutaneous fat (stored under the skin). Reducing visceral and ectopic fat can improve blood sugar control regardless of body weight.

Visceral may lead to health problems because: 1) of its unique metabolic properties, 2) it induces inflammation, and 3) it serves as a marker of ectopic fat. When the body’s ability to store fat under the skin is maxed out, additional fat gets stored in the abdominal area as visceral fat, some of which may later be stored as ectopic fat in organs that aren’t supposed to store fat, such as the liver, pancreas, heart, and skeletal muscles. The amount of under-the-skin fat storage capability ability varies among people. Individuals with relatively small under-the-skin fat storage capacities have low personal fat storage thresholds. Such folks can have relatively little body fat, have a healthy-weight body-mass index, and yet can have high risk of cardiometabolic diseases because their excess fat ends up as visceral and/or ectopic fat. Those of us with a beer belly would do well to shrink it with aerobic exercise and a better diet.

Life’s Simple Seven

In 2010, the American Heart Association published Life’s Simple Seven, metrics that would help patients and clinicians evaluate and monitor cardiovascular health. The seven factors included blood pressure, total cholesterol, blood glucose, physical activity, healthy diet, body mass index, and smoking. Scores ranged from 0-14 with higher scores reflecting better cardiovascular health. A team of researchers used Life’s Simple Seven metrics to predict the amount of ectopic fat and degree of  insulin resistance. Cross-sectional data came from 7,717 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) and the Mediators of Atherosclerosis in South Asians Living in America (MASALA) studies. Ectopic fat was measured using non-contrast computed tomography (CT) scans, the gold standard for such data. Life’s Simple Seven scores were grouped in three categories of low (0-7), intermediate (8-11), and ideal (12-14) cardiovascular health.

Participants with ideal cardiovascular health tended to be younger, female, non-Hispanic white, have higher income, and lack a family history of heart attack. After adjusting for confounding factors and compared to participants with ideal cardiovascular health, participants with poor cardiovascular health had significant 63 percent greater ectopic fat area, 84 percent greater pericardial (around the heart) ectopic fat volume, 41 percent greater intermuscular fat area, and 15 percent higher liver fat. Participants with intermediate cardiovascular health also had significantly greater ectopic fat in all of the above compartments compared to participants with ideal cardiovascular health. In addition, compared with participants with ideal cardiovascular health, those with poor or intermediate cardiovascular health had significantly higher insulin resistance. Ouch!

Ectopic fat in the pancreas and heart

Two Japanese researchers summarized the health consequences of ectopic fat accumulation in the pancreas and the heart. Intracellular accumulation of fat (triglyceride) in pancreatic beta cells appears to compromise their ability to produce insulin, which may lead to glucose intolerance and type 2 diabetes. Ectopic fat accumulation in the heart muscle is linked to reduced diastolic cardiac function and increased risk of cardiovascular disease.

What to do

There seems to be little doubt that ectopic fat stored In your liver, pancreas, and heart damages your health through increased risk of insulin resistance, type 2 diabetes, and cardiovascular disease. You may be tired of hearing this song but ignore it to your peril: Keep Moving and Eat Better.

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