EFFECTS OF ISOENERGETIC, LOW-FAT DIETS ON ENERGY-METABOLISM IN LEAN AND OBESE WOMEN

Whether changing from a high-fat diet to an isoenergetic, low-fat, hig h-complex-carbohydrate diet results in thermogenic benefits is controv ersial. Brief dietary interventions and failure to account for the pot ential influence of body-fat distribution on energy metabolism could h ave confounded the interpretation of previous studies. To address thes e issues, eight upper-body obese, seven lower-body obese, and eight no n-obese premenopausal women underwent measurements of body composition , resting energy expenditure, overnight energy expenditure, and meal f at oxidation at the end of a weight-stabilizing, high-fat (42%) diet, and after 4 wk of an isoenergetic, lowfat (27%) diet. No change in bod y composition, resting energy expenditure, overnight energy expenditur e, or meal fat oxidation occurred. We conclude that isoenergetic shift s from dietary fat to dietary carbohydrate within the generally recomm ended range have little or no effect on energy metabolism, and that bo dy-fat distribution does not predict differences in energy expenditure .