A slight reduction in carbohydrate intake may help decrease a person’s level of dangerous visceral fat, or deep abdominal fat, even if he has not lost any weight, according to a new study funded by the National Institutes of Health. Visceral fat, which surrounds abdominal organs, increases the risk of developing insulin resistance (a component of Type 2 diabetes), heart disease, and various other conditions.
Researchers recruited 69 overweight but healthy men and women. The participants were given food for two consecutive eight-week periods; the first period consisted of a weight-maintenance meal plan, and the second period consisted of a weight-loss meal plan that cut each person’s calories by 1,000 each day. The participants received either a standard lower-fat diet, comprised of 55% of calories from carbohydrate and 27% of calories from fat, or a slightly higher-fat diet that had a modest reduction in the carbohydrate content. This diet, which contained foods that were relatively low on the glycemic index (a ranking of carbohydrate-containing foods based on how quickly they raise blood glucose levels), was comprised of 43% of calories from carbohydrate and 39% of calories from fat. In both diets, the final 18% of calories came from protein. At the beginning and end of each phase of the study, the participants had their visceral fat and total body fat measured using different types of medical scans.
When they analyzed the results, the researchers found that during the weight-loss phase of the study, participants on both of the diets lost weight, but those on the lower-carbohydrate diet averaged a 4% greater loss of total body fat. Moreover, during the weight-maintenance phase, people on the lower-carbohydrate diet were found to have 11% less visceral fat than people on the standard diet. After analyzing these results by race, the researchers determined that this result was exclusive to whites, who generally have more deep abdominal fat than blacks (even when matched for body weight or percent body fat).
According to lead study author Barbara Gower, PhD, decreasing the amount of visceral fat “could help reduce the risk of developing Type 2 diabetes, stroke, and coronary artery disease. For individuals willing to go on a weight-loss diet, a modest reduction in carbohydrate-containing foods may help them preferentially lose fat, rather than lean tissue. The moderately reduced carbohydrate diet allows a variety of foods to meet personal preferences.”
For more information, see the press release “Cut Down On ‘Carbs’ to Reduce Body Fat, Study Authors Say” from The Endocrine Society.