AJP - Regulatory, Integrative and Comparative Physiology, Vol 260, Issue 3 518-R524, Copyright © 1991 by American Physiological Society
Exercise decreases fat selection in female rats during weight cycling
T. Gerardo-Gettens, G. D. Miller, B. A. Horwitz, R. B. McDonald, K. D. Brownell, M. R. Greenwood, J. Rodin and J. S. Stern
Department of Nutrition, University of California, Davis 95616-8669.
Weight cycling (weight loss and regain) increases fat intake in rats
allowed to self-select a diet from protein, carbohydrate, and fat sources.
This study reports the effects of exercise on macronutrient self-selection.
Female Sprague-Dawley rats (5 mo old) self-selected their diet. After 3 wk,
rats were assigned to one of the following three groups: ad libitum fed
sedentary (Con), sedentary food restricted to 40% Con intake (R-Sed), or
treadmill exercised (20 m/min, 1 h/day, 6 day/wk) food restricted to 40%
Con intake (R-Ex). Food restriction was for 3 wk followed by 5 wk of
refeeding. This was repeated for a second cycle. During restriction, body
weight decreased by 30% in R-Sed and by 33% in R-Ex than in R-Sed, fat
regain was greater in R-Sed. By week 3 of refeeding, total caloric
consumption did not differ. However, fat selection increased in R-Sed (56%
kcal) vs. R-Ex (30%) and Con (35%). Fat selection in R-Sed increased
further during cycle 2 (73% kcal). Resting oxygen consumption decreased
during food restriction in R-Sed and R-Ex. After refeeding, resting
metabolic rate in R-Ex was significantly greater than in R-Sed. In
conclusion, weight cycling increases dietary fat selection and adiposity.
Exercise mitigates this effect.
