Dietary fat oxidation as a function of body fat

Background: It is hypothesized that low dietary fat oxidation makes subjects prone to weight gain. Objective: The aim of the study was to determine dietary fat oxidation in normal, overweight, and obese subjects. Design: The subjects were 38 women and 18 men with a mean (SD) age of 30 +/- 12 y and a body mass index (in kg/m(2)) of 25 +/- 4 (range: 18-39). Dietary fat oxidation was measured with deuterated palmitic acid, given simultaneously with breakfast, while the subjects were fed under controlled conditions in a respiration chamber. Body composition was measured by hydrodensitometry and deuterium dilution. Results: Dietary fat oxidation, measured over 12 h after breakfast, ranged from 4% to 28% with a mean (+/- SD) of 16 +/- 6%. Dietary fat oxidation was negatively related to percentage body fat, and lean subjects had the highest and obese subjects the lowest values (r = -0.65, P < 0.001). Conclusion: The observed reduction in dietary fat oxidation in subjects with a higher percentage body fat may play a role in human obesity.