Resting Energy Expenditure Changes With Weight Loss: Racial Differences

Abstract

Resting energy expenditure changes with weight loss: racial differences It is controversial whether weight loss reduces resting energy expenditure (REE) to a different magnitude in black and white women. PURPOSE: To determine whether changes in REE with weight loss were different between black and white postmenopausal women, and whether changes in body composition (including regional lean and fat mass) were associated with REE changes within each race. METHODS: Black (n= 26) and white (n= 65) women (age= 58.2±5.4 years, 25< BMI< 40 kg·m-2) completed a 20-week weight loss intervention involving caloric restriction and aerobic exercise training. Body weight, lean and fat mass (total body, limb and trunk) via dual energy X-ray absorptiometry, and REE via indirect calorimetry were measured before and after the intervention. RESULTS: Baseline REE positively correlated with body weight, lean and fat mass (total, limb, and trunk) in white women only (p< 0.05 for all). The intervention decreased absolute REE in both races similarly (1279±162 to 1204±169 kcal·day-1 in blacks; 1315±200 to 1209±185 kcal·day-1 in whites). REE remained decreased after adjusting for changes in total or limb lean mass in black (1302 to 1182 kcal·day-1, p= 0.043; 1298 to 1144 kcal·day-1, p= 0.006, respectively), but not white, women. Changes in REE correlated with changes in body weight (partial r = 0.277) and fat mass (partial r= 0.295, 0.275, and 0.254 for total, limb, and trunk, respectively; p< 0.05) independent of baseline REE in white women. CONCLUSION: With weight loss, REE decreased in proportion to the amount of fat and lean mass lost in white, but not black, women. Supported by NIH R01 grant R01-AG/DK20583, Wake Forest University Claude D. Pepper Older Americans Independence Center (P30-AG21332), and Wake Forest University General Clinical Research Center (M01-RR07122).