Changes in actual versus defended body weight elicited by a varied, palatable (″supermarket″) diet in rats

Male rats fed on a varied, palatable supermarket diet for 11 weeks gained more weight than chow-fed controls. When palatable food was discontinued, their body weights became static, but remained significantly higher than control weights for a further 5 weeks. Hoarding of food was readily elicited by food deprivation in the dietarily obese as well as in the chow-fed rats. Previous studies have shown that the critical body weight at which hoarding appears does not covary with body weight, but appears to reflect a defended level of body weight. In the present study, critical weights were not significantly different between groups before supermarket diet, but were significantly higher in the supermarket rats after obesity had developed. Thus, the increase in body weight brought about by a supermarket diet (unlike that in ventromedial hypothalamic obesity) can be accompanied by an increase in the defended level of body weight as inferred from the critical weight for the onset of hoarding behaviour. © 1985.