Caloric Expenditure in the Morbidly Obese Using Dual Energy X-ray Absorptiometry

Abstract 

Total caloric expenditure is the sum of resting energy expenditure (REE) and caloric expenditure during physical activity. In this study, we examined total caloric expenditure in 25 morbidly obese patients (body mass index≥35 kg/m²) using dual energy X-ray absorptiometry (DXA) scanning and cardiorespiratory exercise testing. Our results show average REE for all individuals was 2027±276 kcal/d and mean net caloric expenditure during 30 min of exercise was 115±16 kcals. Assuming the mean of all input values, a strict 1500 kcal/d diet combined with 150 min per wk of structured physical activity, the projected weight change was −7% (8.8±6.2 kg) for 6 mo. We conclude that morbidly obese individuals should be able to achieve only a modest weight loss by following minimal national guidelines. These data suggest that more aggressive energy expenditure and caloric restriction targets for long periods of time are needed to result in significant weight loss in this population.

Key Words: Body composition, caloric expenditure, cardiorespiratory fitness, dual energy X-ray absorptiometry, exercise, weight loss