High-fat hypocaloric diet modifies carbohydrate utilization of obese rats during weight loss

The effects of fat content in the hypocaloric diet on whole body glucose ox idation and adipocyte glucose transport were investigated in two animal-fee ding experiments. Diet-induced obese rats were food restricted to 75% of th eir previous energy intakes with either a high (45% by calorie) or a low (1 2% by calorie) corn oil diet for 9 wk (experiment 1) or 10 days (experiment 2). The losses of body weight (P < 0.05) and adipose depot weight (P < 0.0 5) were less in the 45% compared with the 12% fat group. During the dynamic phase of weight loss (day 10 of food restriction), plasma glucose and insu lin concentrations were higher (P < 0.05) in the 45% than those in the 12% fat group. Whole body carbohydrate oxidation rate in response to an oral lo ad of glucose was increased (P < 0.001) by food restriction in both dietary groups; however, carbohydrate oxidation rates were lower (P < 0.01) in the 45% than in the 12% fat-fed rats during the weight loss period. Adipocyte glucose transport was greater (P < 0.02) in the 45% than in the 12% fat gro up in an intra-abdominal adipose depot but not in subcutaneous fat. These d ata suggest that dietary fat content modifies whole body glucose oxidation and intra-abdominal adipocyte glucose uptake during weight loss.