Intermittent fasting may be effective for weight loss, cardiometabolic health | Harvard T.H. Chan School of Public Health
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Intermittent fasting may be effective for weight loss, cardiometabolic health
Intermittent fasting diets may be as effective for weight loss and cardiometabolic health as traditional calorie-restricted diets, according to a new study. Of all forms of intermittent fasting, alternate day fasting was most effective. The study was published June 18 in The BMJ. Despite intermittent fasting’s potential effectiveness, it isn’t the right dietary or lifestyle choice for everyone, the researchers said. The average body mass index among participants was 31, and nearly 90% had existing health conditions. The researchers noted that most of the clinical trials lasted less than 24 weeks and that much more research is needed on intermittent fasting’s long-term health impacts. They added that as with any dietary change, it is important to consult with health care providers.
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Intermittent fasting diets—in which a person cycles between scheduled windows of eating and fasting—may be as effective for weight loss and cardiometabolic health as traditional calorie-restricted diets, according to a new study co-authored by researchers at Harvard T.H. Chan School of Public Health. Of all forms of intermittent fasting, alternate day fasting—in which a person fasts for a full day, every other day—was most effective.
The study was published June 18 in The BMJ. Zhila Semnani-Azad, postdoctoral research fellow in the Department of Nutrition, was the lead author. Frank Hu, Fredrick J. Stare Professor of Nutrition and Epidemiology and chair of the Department of Nutrition, was a co-author.
Despite intermittent fasting’s growing popularity, much remains unclear about its health effects. To fill this gap, the researchers conducted a systematic review and network meta-analysis of clinical trials that compared how intermittent fasting diets, traditional calorie-restricted diets, and restriction-free diets impacted participants’ body weight and various measures of cardiometabolic health. The average body mass index among participants was 31, and nearly 90% had existing health conditions. The intermittent fasting diets tested were alternate day fasting, time restricted eating (such as the 16:8 diet, composed of a 16-hour fasting window and an eight-hour eating window), and whole day fasting (such as the 5:2 diet, composed of five days of unrestricted eating and two days of fasting).
The study represents the largest systematic review on intermittent fasting, analyzing 99 clinical trials across more than 6,500 participants. Researchers found that for weight loss, intermittent fasting and traditional calorie-restricted diets were on par and were more effective than restriction-free diets. However, alternate day fasting demonstrated superior results, resulting in 1.3 kilograms greater weight loss compared to traditional calorie-restricted diets, as well as improvements in several other body measurements related to cardiometabolic risk, including waist circumference, cholesterol and triglyceride levels, and c-reactive protein, an indicator of inflammation.
The researchers noted that most of the clinical trials lasted less than 24 weeks and that much more research is needed on intermittent fasting’s long-term health impacts. Semnani-Azad added that despite intermittent fasting’s potential effectiveness, it isn’t the right dietary or lifestyle choice for everyone. “As with any dietary change, it is important to consult with health care providers and to consider one’s medical history, dietary preferences, social environment, and realistic long-term compliance,” she said.
Read the study
Intermittent fasting strategies and their effects on body weight and other cardiometabolic risk factors: systematic review and network meta-analysis of randomised clinical trials
Read a BMJ press release
Intermittent fasting comparable to traditional diets for weight loss
About The Author Maya Brownstein Media Relations Manager in the Office of Communications
Featured in this article Zhila Semnani-Azad Research Fellow