Abstract P022: Determinants of Energy Balance: Differences Related to Body Weight and Body Composition

Abstract

Conversion, utilization and storage of energy in the regulation of energy balance is poorly understood. These misconceptions arise from confusion related to energy balance and its impact on body weight and composition, and can bias the interpretation of findings that are important for the development of policies addressing the obesity epidemic. PURPOSE: Our purpose was to examine the regulation of interactions between total daily energy intake (TDEI) and energy expenditure (TDEE) in healthy adults. METHODS: Adults not limited by gender, race or ethnicity (n=430; aged 21 to 40; BMI of 20 to 35) participated in a battery of physiological, anthropomorphic, behavioral and psychological measurements that are associated with energy balance regulation. The primary components of energy balance regulation (TDEI and TDEE) were measured by 3 random 24-hour dietary recalls and SenseWear accelerometry, respectively. Body composition was determined by dual x-ray absorptiometry (DXA). Absolute and relative resting metabolic rates (aRMR and rRMR) were determined through hooded indirect calorimetry. General linear modeling was used to examine the relationships of weight and body fatness with TDEI and macronutrient composition as well as the largest components of TDEE including aRMR, rRMR and physical activity energy expenditure (PAEE). In addition, data were compared between participants with a healthy body fat % (below 25; n=123) and obese (at or above 30%; n=241). RESULTS: All results were adjusted for age, gender and race. TDEE was positively associated (r=.47, p<.001) with TDEI. There was a positive association between aRMR (L/min) and weight (r=.743, p<.001). By contrast, rRMR (ml/kg/min) was inversely correlated with body weight (r= -.38; p<.001). TDEI was significantly higher in the lean group (2465±66 to 1878±42, p<.001) with no measureable differences in macronutrient percentages. The lean group had a higher TDEE and PAEE as compared to the obese group. CONCLUSIONS: There was a robust matching of TDEI and TDEE across weight and body composition ranges. Heavy people burned more calories than lighter people although the lighter individuals had a higher rRMR. The leaner group had a higher TDEI, reflecting a potential regulation based on the greater TDEE in this group. Further, the increased TDEE could be explained by the higher PAEE (approximately 500 kcal) in leaner individuals. These findings emphasize that energy expenditure is related to mass rather than body composition. The regulation of energy intake and body composition is multifactorial, with PAEE a significant determinant for energy storage. This study was funded through an unrestricted grant from The Coca-Cola Company.