Diet composition affects weight gain, adiposity and blood parameters in healthy human volunteers

This study examined the effect of diet composition on weight gain and body composition during a controlled overfeeding program. In weight reducing regimens, the body is energy blind and dietary energy rather than diet composition appears to be the greatest determinant of changes in weight and body composition. However, in overfeeding, both diet composition and excess energy intake are being implicated in obesity. Sixteen healthy adult subjects were overfed, 40% above their maintenance energy requirements, diets high in fat (50%) or carbohydrates (CHO) (60%) for a period of 4 weeks. Eight subjects were assigned to each of the experimental diets. Body weight, body composition, adiposity, serum lipids, insulin and glucose were measured in all subjects before and at the end of the feeding period. An Excess Energy Efficiency Factor (EEEF) was calculated as body energy gain per excess dietary energy. Results showed that adiposity was significantly higher in the high fat as compared to the high CHO fed group. EEEF was higher on the high fat as compared to high CHO diet. HDL-cholesterol was higher in subjects consuming the high fat as compared to those on the high CHO diet. This study shows that under conditions of excess energy intake, a high fat diet is more efficient in increasing adiposity and fat deposition as compared to high carbohydrate diet. The relative efficiency of macronutrients on body composition when fed at maintenance energy requirements remains to be investigated. (C) 1999 Elsevier Science Inc.