title: Contribution of decreased body mass to diminished thermic effect of exercise in reduced-obese men.
abstract: Reduced energy expenditure after weight loss contributes to the difficulty which obese individuals face in maintaining a lower body weight. To evaluate the contribution of decreased energy cost of physical activity at a lower body weight to diminished total energy expenditure, two groups of unconfined obese men were studied before and after a 22 percent weight loss. A control group received a 700-cal diet alone whereas the experimental group, while consuming an identical diet, wore a vest into which weights were inserted twice weekly to exactly compensate for body weight loss. In the control group the total daily caloric requirement for weight maintenance fell by 916 +/- 121 kcal/day (3834 +/- 507 kJ/day) in contrast to only a 404 +/- 192 kcal/day (1691 +/- 804 kJ/day) fall in the experimental group at full exogenous weight replacement (P less than 0.001). Body composition, maximal exercise performance, and resting metabolic rate were unaffected by weight replacement. Activity levels decreased at the same rate in both subject groups with progressive weight loss. In conclusion, loss of body weight reduces the energy cost of physical activity sufficiently to account for more than half of the major fall in energy expenditure noted in free-living men after weight loss.
authors.affiliation: Department of Medicine, University of Washington, Seattle.
authors.forename: D S
authors.initials: DS
authors.lastname: Weigle
mesh_terms: D000273:Adipose Tissue / Q000503:physiopathology; D000328:Adult; D001823:Body Composition; D001833:Body Temperature Regulation; D001835:Body Weight; D004038:Diet, Reducing; D004734:Energy Metabolism; D005080:Exercise Test; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000178:diet therapy* / Q000503:physiopathology; D015431:Weight Loss