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

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. 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. 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. Repeated water fasting was not only ineffective for weight loss but also increased the body weight of fasting mice.