Regulation of energy balance in two models of reversible obesity in the rat.

Reports on 2 experiments with 114 adult male Sprague-Dawley rats. Ss were made obese either by tube feeding varying fractions (34, 47, 68, or 75%) of their normal food intake or by offering them a varied and palatable diet (cafeteria diet). After 17–30 days of these regimens, the treatments were withdrawn, and Ss were allowed free access to the normal stock diet. Tube-fed Ss precisely adjusted voluntary food intake to compensate for the energy delivered by tube but nevertheless became obese as a result of an increased metabolic efficiency. Cafeteria-fed Ss were hyperphagic and became obese without any apparent change in metabolic efficiency. Recovery from obesity was more rapid in cafeteria Ss and was due to a pronounced increase in heat production as well as concomitant hypophagia. Ss previously made obese by tube feeding exhibited hypophagia and returned to normal weight without any change in heat production. The relevance of these results to the concept of lipostasis and the relative roles of energy intake and expenditure in the regulation of energy balance are discussed. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)