Long-Term Yo-Yo Dieting Exaggerates Liver Steatosis and Lesions but Preserves Muscle Performance in Male Zebrafish

Abstract

Weight regain within one year after weight loss is frequently observed and is referred to as yo-yo dieting or weight cycling. In this study, we explore the effects of yo-yo dieting on the liver, adipose tissue, and muscle characteristics of male zebrafish. Four-month-old AB wild-type male zebrafish were randomly assigned to three groups: high-calorie intake (H, seven meals per day), low-calorie intake (L, two meals per day), and yo-yo diet (the low- and high-calorie alternation switched every two weeks) groups. Feeding the fish the H diet for over 8 weeks led to steatosis and damage to the liver. The yo-yo diet reduced liver lipid accumulation at week eight but caused a similar degree of lipid accumulation as the H diet thereafter. It was found that twenty weeks of yo-yo dieting actually exacerbated hepatic damage. Compared to the L diet, feeding the fish on the yo-yo and H diets for a period of 20 weeks significantly increased the size of muscle fibers, resulting in higher speed during burst swimming and a significant increase in the size and number of adipocytes in the abdominal tissue. To summarize, short-term yo-yo dieting was found to attenuate hepatosteatosis and maintain fast-twitch muscle function. Long-term yo-yo dieting preserved fast-twitch muscle function and muscle fiber size; however, it exacerbated the pathological changes in the liver.