Effects of long-term cycling between palatable cafeteria diet and regular chow on intake, eating patterns, and response to saccharin and sucrose

When exposed to a diet containing foods that are rich in fat and sugar, rats eat to excess and gain weight. We examined the effects of alternating this diet with laboratory chow on intake of each type of diet, the eating elicited by a palatable food (biscuits), and the drinking elicited by sweet solutions that did (sucrose) or did not (saccharin) contain calories. Each week for 13 weeks, cycled rats were provided with the cafeteria diet for three successive days/nights and the chow diet for the remaining four days/nights, whereas other rats received continuous access to either the cafeteria or the chow diets. On each of the 13 weeks, cycled rats ate more across the first 24 hour exposure to the cafeteria diet than rats continuously fed this diet. In contrast, cycled rats ate less across the first 24 hour exposure to the chow diet than rats continuously fed this diet and ate less when presented a novel palatable biscuit than chow-fed rats. The three groups exhibited similar licks per cluster to saccharin, but cafeteria-fed and cycled rats showed fewer clusters than chow-fed rats. In contrast, chow-fed rats and cycled rats exhibited more licks per cluster to sucrose than cafeteria-fed rats, but all three groups had a similar number of clusters. The results were discussed in relation to the effects of diet cycling on eating patterns, body weight, and 'wanting' and 'liking'. These findings with rats may have important implications for yo-yo dieting in people.