The results of this preliminary study were presented The Endocrine Society's 91st Annual Meeting in Washington, D.C., in June of this year.
"There has been great public interest in low-carbohydrate diets for weight loss, but they are difficult to maintain, in part because of the drastic reduction in carbohydrates," said co-author Barbara Gower, PhD, a professor in the Department of Nutrition Sciences, University of Alabama at Birmingham.
Gower and her colleagues investigated whether a moderate reduction in carbohydrates would help people feel more full than they feel when eating the typical, high-carbohydrate diet found in the US. In the US, the standard diet includes about 55% carbohydrates, including sugars, starches, and fibre. The diet used as a control diet for this study was similar. The moderately reduced carbohydrate diet included 43% of calories from carbohydrates. The moderate-carb diet included 37% fat, while the standard diet included 27% fat. Protein intake on both diets was the same (18% of calories) because protein also affects feelings of fullness and the secretion of insulin.
Participants were assigned to one of the two groups and consumed the diet for one month. The total calories were sufficient to maintain their weight during the study period. They were weighed every weekday, and food intake was adjusted weekly so that they would not lose or gain weight. After four weeks, the participants had adjusted to their diet and they consumed a test breakfast specific to their diet.
Before and after the test meal, the subjects’ insulin and blood glucose levels were measured. Each person was asked to rate his or her feeling of fullness or hunger. Insulin and glucose responses were measured because they are known to affect feelings of fullness.
Results showed that the modest reduction in carbohydrates lowered insulin levels and stabilised blood sugar levels after a meal, even in the absence of weight loss. Participants rated their feelings of fullness higher with the moderate-carbohydrate diet, than with the standard diet and their feelings of fullness lasted longer after eating.
"Over the long run a sustained modest reduction in carbohydrate intake may help to reduce energy consumption and facilitate weight loss," Gower said.