Impact of Short‐term, Repeated Water Fasting on the Weight of Mice

Introduction: Caloric restriction is a strategy applied for weight loss. Water fasting is a popular way for obesity treatment. However, little is known about the impact of water fasting on weight. Therefore, this study was conducted to investigate the effect of short-term, repeated water fasting on the weight of mice. Methods: In this study, the physiological effect of short-term, repeated water fasting on the weight of female mice was evaluated. At 6 weeks of age, mice were randomly assigned to either repeated-fasting or control group (fed ad libitum). Each group consisted of twenty mice. As the fasting period started, the repeated-fasting group had access to only water; animals had free access to food and water on non-fasting days. Body weight of each group before, during, and after the fasting period was recorded. Results: Body weight of the fasting group significantly decreased, unlike the control group. However, the fasting group gained weight rapidly after being re-fed and became significantly heavier than mice in the control group (P < 0.01). Interestingly, the average body weight of the fasting group increased, compared to that of the control group; in fact, the fasting mice weighed approximately 10% heavier than the control ones. Conclusion: Repeated water fasting was not only ineffective for weight loss but also increased the body weight of fasting mice.