The Effects of Fat Distribution on Resting Energy Expenditure in Premenopausal Morbidly Obese Females

Background: upper body, or abdominal, distribution of body fat is associated with a number of metabolic and hormonal aberrations that could influence resting energy expenditure REE. The purpose of our study was to examine the effects of fat distribution on REE of 96 morbidly obese premenopausal females. Methods: the study population consisted of three groups of study subjects, 32 with lower body fat distribution (LBD) and waist-to-hip circumference ratios WHR < 0.80, 20 with intermediate (INT) fat distribution and WHR between 0.80 and 0.85 and 34 females with upper body distribution of fat (UBD) and WHR > 0.85. Indices measured included: (1) REE; (2) maximal oxygen consumption during an exercise tolerance test (VO_2max); (3) basal respiratory quotient (RQ); (4) fasting blood glucose; and (5) serum cholesterol and triglycerides. Results: we found that morbidly obese women who store fat abdominally (WHR > 0.80) have significantly (p < 0.01) higher REE (kcal per h per BSA) than those with lower body obesity. Levels of triglyceride and glucose of the UBD group were also higher than those of the LBD subjects, i.e. 35% and 23%, respectively. VO_2max and RQ were similar between the study groups, suggesting that the elevated REE of the patients with abdominal adiposity were likely not the result of their greater muscle mass or differences in substrate utilization. Conclusion: fat distribution affects REE in morbidly obese premenopausal females, and further research is needed to identify the various entities regulating REE in the morbidly obese.