Effects of Weight Cycling on Food Efficiency and Metabolic Parameters in Rats

Abstract

0530 On the context of the epidemic number of obesity cases worldwide, low rate of success in weight loss attempts and high number of people trying to lose weight, the routine of weight cycling (WC) acquires clinical importance. It is possible that repeated cycles of weight loss and regain affect the metabolism and food efficiency (FE). Besides, there is little information about the influence of the supplementation (S) of some amino acids (AA) on the effects of the WC. PURPOSE: To determine the influence of the WC routine, the chronic S of L-leucine (LEU) and L-phenylalanine (PHE) on the FE and metabolism in rats. METHODS: 30 adult male Wistar rats were divided in 5 groups: ad libitum (AL), pair fed (PF), weight cycling (WC0), WC + 50% of AA S (WC50) and WC + 100% of AA S (WC100). The AL, PF and WC0 groups were fed with a powdered chow diet in accordance to the American Institute of Nutrition recommendations (93M). The WC50 and WC100 groups were fed with a similar chow diet, but with additional LEU+PHE, increasing by 50 and 100%, respectively, the amount of ingestion of these AA. The AL animals had free access to food, while the WC0, WC50 and WC100 groups underwent 3 cycles consisting each one of: 1 week of 50% food restriction, followed by 2 weeks of ad libitum intake. The PF group intake was kept steady during the experiment, but it was restricted according to the total average intake of WC0, WC50 and WC100 groups. RESULTS: AL total food intake was the highest compared to the other groups (average: 12.92%, p<0.0001), with no other difference between the groups. The final weight and weight gain of all groups were higher than in the PF group, but reached statistical significance only on the AL and WC50 groups (p<0.05). There was no significant difference between groups in relation to fat% in carcass, plasmatic glucose, serum albumin, triglycerides, serum total protein, gastrocnemius and soleus glycogen, and hepatic protein. Hepatic glycogen in the PF group was the highest (average: 734%, p<0.0001). Gastrocnemius protein in AL was higher than in PF and WC50 groups (11.3 and 9.5%, p<0.01) CONCLUSION: Rats subjected to WC routine and fed with the same amount of food showed an increased FE and, consequently, an higher weight gain. The LEU+PHE S augmented this response. Acknowledgment: CAPES and CNPq – Brazil