Dietary Fat Oxidation and 24h Fat Oxidation Were Not Different Between Asians and Caucasians Despite Differences in Body Composition

Objective This study aimed to determine the difference in body composition and its effect on 24 hour fat oxidation and dietary fat oxidation between Asians and Caucasians.

Methods Seventeen Asians, (8 males) were matched for BMI, age and gender with 17 Caucasians. Physical activity was measured for 7 days with an accelerometer, followed by a 3-day energy balance diet. Energy expenditure and substrate utilization were measured for 24 hours in a respiration chamber, with subjects fed in energy balance. Dietary fat oxidation was determined from the percentage recovery of deuterium in the urine, following a breakfast meal containing deuterated palmitic acid. Body composition was calculated with a 3-compartment model from body mass, body volume (hydro-densitometry) and total body water (deuterium dilution).

Results Asians had a higher % body fat than Caucasians (28.1±7.3 versus 23.0±6.9%) for Asians and Caucasians respectively. Dietary fat oxidation was 11.7±3.6 versus 10.8±4.5% for Asians and Caucasians respectively. The 24h fat oxidation as a percentage of total energy expenditure was 17.8±6.9 versus 19.2±5.1%. Carbohydrate and protein oxidation was 68.5±6.9versus 66.8±5.1% and 14.5±2.3 versus 14.9±1.7%, for Asians and Caucasians respectively. In a model including ethnicity, energy balance, spontaneous physical activity in the respiration chamber and the daily physical activity level as independent variables, only spontaneous physical activity in the respiration chamber had a significant effect on dietary fat oxidation.

Conclusion Dietary fat oxidation and 24h fat oxidation were not different between Asians and Caucasians despite differences in body composition.