Yo-yo dieting impairs reproduction performance in female zebrafish (Danio rerio)

Background: Weight management is crucial for improving fertility rates in the obese population. However, many individuals regain lost weight within 2 to 5 years, creating uncertainty around the effects of weight fluctuations on reproduction. This study used a zebrafish model to investigate the impact of yo-yo dieting on female fecundity and the role of adipose tissue and liver in reproductive regulation. Methods: Female zebrafish underwent alternating high-energy (H) and low-energy (L) diets for 8 weeks to induce yo-yo dieting, with fecundity analyzed at the end. Results: The H diet led to weight gain and hyperglycemia, while the LH diet caused weight fluctuation. There were no significant differences in stage 4 oocyte percentages, but atretic follicles were observed in the H and LH groups. Offspring survival rates at 3 dpf were 94.5% (L), 64.8% (H), and 59.7% (LH). H larvae at 5 dpf had the longest size, followed by LH, while L larvae were the shortest. H and LH fish showed increased lipid accumulation in adipose tissues, with the H liver exhibiting more hepatic steatosis. Both the H and LH fish exhibited muscular hypertrophy. In summary, yo-yo dieting negatively affected fecundity, potentially due to the impact of adipose tissue.