THE EFFECT OF CAFETERIA FEEDING ON ENERGY-BALANCE IN LEAN AND OBESE ZUCKER RATS

A 6-item cafeteria diet was given to 30-day lean and obese Zucker rats for two successive 15-day periods, the consumption of energy and meta bolic substrates and different foods was compared with those of rats f ed a standard reference diet. Cafeteria feeding and obesity had a part ly superimposable effect on lean body mass and fat accrual. Rats' inta ke was grossly hyperlipidic when receiving a cafeteria diet, but their protein and total carbohydrate intake were similar in absolute terms to those of controls. More than half the carbohydrate intake of cafete ria rats was made up of oligosaccharides. Obese rats consumed more fat ty and sweet foods than lean animals. There was a direct relationship established between the amount of oligosaccharides consumed and the sh are of absorbed energy being deposited as fat. Both obesity and cafete ria feeding induced hyperphagia. The energy available (heat) in each g roup was, nevertheless, higher in cafeteria-fed obese rats than in tho se on the reference diet, but most differences were lost in obese rats when expressed as a function of LBM(-0.75) (lean body mass). This uni form value was higher than that of lean rats on the reference diet, su ggesting that the heat production per unit of lean body mass of obese rats was not influenced by diet. Heat production was maintained as a w ay to keep the thermal homeostasis of the rat within functional levels .