Journal of Applied Physiology, Vol 70, Issue 5 2303-2310, Copyright © 1991 by American Physiological Society
Exercise training elevates RMR during moderate but not severe dietary restriction in obese male rats
D. L. Ballor
Department of Psychology, University of Wisconsin, Madison 53706.
This study examined the effects of 11 wk of exercise training (E) on
resting O2 uptake (RMR) and the composition of diet-induced weight loss in
obese male Sprague-Dawley rats (n = 48). The rats underwent one of three
levels of dietary treatment: ad libitum (AL), moderate restriction (MR),
and severe restriction (SR). Compared with AL-CC (cage confined; 647 +/- 13
g), the AL-E (84% of AL-CC), MR-CC (77%), MR-E (77%), SR-CC (63%), and SR-E
(63%) groups were all reduced in body mass. At the MR level, E
significantly reduced fat mass (FM; MR-CC 73 +/- 5, MR-E 45 +/- 5 g) and
increased water mass (WM; MR-CC 307 +/- 5, MR-E 329 +/- 5 g) compared with
CC. In contrast, no significant differences existed between the SR-CC and
SR-E groups. Exercise training did not result in conservation of protein
mass at any level of dietary intake. Exercise training significantly
elevated RMR (on a kg0.75 basis) by approximately 7% for the AL-E and MR-E
groups compared with their respective dietary counterparts. These findings
may help reconcile the conflicting results present in the literature with
respect to the effects of exercise training during diet-induced weight
loss. That is, studies using relatively severe dietary restrictions are
less likely to demonstrate exercise-induced changes in RMR, FM, and WM than
those employing moderate dietary restrictions.
