Intermittent Fasting Could Cause Loss of Muscle Mass: Study


Oct 1, 2020


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Intermittent fasting is a pervasive weight-loss strategy, with millions on the Internet documenting their experiences of weight loss. The premise is that abstaining from eating for long stretches of time each day will lower insulin levels in the body, which in turn makes the body burn fat faster than usual. Previous research surrounding intermittent fasting has also shown positive results, deeming it a successful method to lose and keep off excess weight.

That is, until now. New research published in JAMA Internal Medicine contests these claims, saying that such time-restricted eating leads to minimal weight loss. Plus, the study’s participants, who were all overweight/obese individuals, lost a lot more muscle mass than usually expected, which adds to the growing concern regarding intermittent fasting’s usefulness.

Dr. Ethan Weiss, a co-author of the study who also personally practiced intermittent fasting said to CNBC, “I went into this hoping to demonstrate that this thing I’ve been doing for years works…But as soon as I saw the data, I stopped.”

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The small, 12-week study of 116 overweight or obese individuals were divided into two groups — the consistent meal timing group and the time-restricted eating group, who followed the 16:8-hour intermittent fasting formula. Researchers found only a modest decrease (1.17%) in weight for the restricted group, in comparison to the 0.75% decrease in weight in the control group.

Apart from this, scientists also observed a significant decrease in muscle mass in the time restricted group. Losing muscle mass is detrimental to strength and mobility. Scientists estimate that this loss of muscle mass is linked to insufficient protein consumption at odd times, as both the number of meals and the timings of meals affect the presence of muscle mass in the body.

Beyond the physical effects of intermittent fasting, researchers have also cautioned potential adapters about the mental implications of heavily controlling food intake. Research published in Behavioral Sciences theorized that intermittent fasting could promote erratic eating patterns, binging, and low mood. Another paper in Current Obesity Reports also calls for further research to establish the mental health effects and eating disorder risks of such restrictive eating.

Dr. Weiss told the New York Times that more research is necessary to further establish these findings. But, he also maintains that his findings encourage skepticism regarding the popular fasting practice. He said, “This was a short study, but it was enough of a study that to me it calls into question whether this works — and if it does work, then the magnitude of the benefit is very small.”


Written By Aditi Murti

Aditi Murti is a culture writer at The Swaddle. Previously, she worked as a freelance journalist focused on gender and cities. Find her on social media @aditimurti.


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