Could on-and-off fasting help prevent obesity?

TORONTO – How often you eat may be as important as how much you eat, reveals a new study led by scientists at The Hospital for Sick Children (SickKids).

Researchers examined the effect of an intermittent-fasting regimen, without restricting caloric intake, in mice. They found that an ‘on-and-off’ fasting regimen not only prevented obesity in mice, but also improved metabolism by changing the quality of fat in the body. The study is published in the Oct. 17 online edition of Cell Research.

Intermittent-fasting is when one temporarily stops eating for a period of time, returns to normal food consumption, and then temporarily stops again.

“Our findings show that the health of the mice is significantly influenced by daily eating patterns. The addition of a ‘stop eating’ period converted inflammatory fat to brown-like (or beige) fat by anti-inflammatory immune cells, meaning it changed bad fat into good fat,” says Dr. Hoon-Ki Sung, co-Principal Investigator of the study, Scientist in Translational Medicine and Northbridge Financial Corporation Catalyst Scholar for Healthy Active Kids at SickKids and Assistant Professor in Laboratory Medicine & Pathobiology at the University of Toronto. “The results are exciting, because they show that weight loss is not the sole benefit of fasting. Fasting also restores the dual function of fat cells, which is to store energy and to release energy.”

Despite extensive research and ongoing treatment and prevention efforts, the prevalence of obesity and associated health issues are increasing. While intermittent-fasting is not a new concept to clinicians and researchers alike, little was known about the molecular mechanisms and metabolic benefit of such a regimen. The aim of the study was to explore the therapeutic and preventative potential of intermittent-fasting regimens.

They discovered that introducing a “stop eating” period is essential to activating anti-inflammatory immune cells which transformed white fat (bad fat) into beige fat (good fat).

While the results are promising, the research team emphasizes that testing an on-and-off fasting regimen in an animal model is very different from what is practical and safe for humans. However, they say the work offers proof-of-principle that there is a metabolic benefit to the “stop eating” period. The next steps are to assess how this knowledge can be practically applied to management and prevention of obesity and metabolic diseases, such as Type 2 diabetes.

“Our findings suggest that fasting may provide an alternative and sustainable way of keeping your body (fat) healthy without reducing your caloric intake,” says Dr. Chi-Chung Hui, co-principal investigator of this study, Senior Scientist in Developmental & Stem Cell Biology and Professor in the Department of Molecular Genetics at the University of Toronto. “We look forward to testing whether this ‘stop eating’ period brings similar metabolic benefit in humans and learning how it could affect the health of body fat.”

This research was supported by grants from Canadian Institutes of Health Research, Banting & Best Diabetes Centre of University of Toronto and SickKids Foundation.

This paper is an example of how SickKids is contributing to making Ontario Healthier, Wealthier and Smarter.

The Hospital for Sick Children