Consuming less calories and increasing physical activity is usually what people do to lose weight and stay healthy. But some people prefer to adopt a diet which consists of eating as much as they want one day while fasting the next. On each fasting day, these people consume energy-free beverages, tea, coffee, and sugar-free gum and they drink as much water as they need. Although many people claim that this diet, called alternate-day fasting (ADF), help them lose weight and improved their health, the effects on health and disease risk of ADF are not clear.

Krista Varady and colleagues studied the effects of alternate-day fasting on 24 male mice for four weeks. To assess the impact of ADF on the health of the mice, the scientists not only tested mice that followed and didn’t follow an ADF diet, but they also studied mice that followed the diet only partially: a group of mice consumed 50 percent of their regular diet every other day (ADF-50%) and another consumed 75 percent of their regular diet every other day (ADF-25%).

The scientists noticed that the mice that followed the complete ADF diet (ADF-100%) lost weight and that the fat cells of both the ADF-100% and ADF-50% groups shrunk by more than half and by 35 percent, respectively. Also, in these two groups of mice, fat under the skin – but not abdominal fat – was broken down more than in mice that did not follow the diet.

These results suggest that complete and modified ADF regimens seem to protect against obesity and type 2 diabetes but do not result in fat or weight loss. More studies will be needed to confirm whether the long-term effects of ADF regimens are beneficial for health and reduce disease risk, the scientists conclude.-American Society for Biochemistry and Molecular Biology