How Intermittent Fasting Can Benefit Your Immune System

The latest science suggests that intermittent fasting may help your body's defenses. Here's what you need to know.

Published on August 3, 2021

A recent review in the journal Immunology Letters suggests that the timing of meals can give your immune system an edge.

"Intermittent fasting increases the rate of autophagy [cell recycling] and, therefore, decreases the amount of inflammation in the body," says Jamal Uddin, Ph.D., a co-author of the study. "This in turn lets the immune system more efficiently spend its resources fighting off illness."

In a nutshell, the extended calorie drought prompts your body to look for a refuel by converting damaged cells into nutrients, which reduces inflammation caused by those cells, says Herman Pontzer, Ph.D., the author of Burn (Buy It, $20, amazon.com), a new look at metabolism.

Here's How Intermittent Fasting Might Benefit Your Immune System , A plate seen from above with the knife and fork arranged to resemble the hands of a clock with food arranged to illustrate the concept of intermittent fasting — Getty Images

The Math Behind Fasting

What time frame triggers this calorie-restricted signal to the body? An earlier analysis of intermittent fasting in the New England Journal of Medicine found that fitting meals into six-or eight-hour windows (say, from noon to 6 p.m. or 11 a.m. to 7 p.m.) is beneficial in reducing inflammation compared with a typical day of eating, but a 12-hour window is less so, says Mark Mattson, Ph.D., a coauthor of the study. (

But you do reap some benefits without being at the more restrictive end, says Marie Spano, R.D.N., a sports dietitian and the lead author of Nutrition for Sport, Exercise, and Health. "Short-term studies using time-restricted eating, where food is restricted to 13-hour windows or less [like 7 a.m. to 8 p.m.], show it can help decrease inflammation."

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How to Try Intermittent Fasting

If you're looking to shrink your eating window, Mattson suggests you do so gradually to acclimate with fewer hunger pangs. If a six- or eight-hour eating period is your aim, Spano recommends "making your meals nutrient dense and eating a meal at the start of your window, in the middle, and at the end." Protein is best spaced out every three to five hours for maximum muscle maintenance and gain, for instance.

To further fend off inflammation, keep up the exercise. "When your body adjusts to spending more of its energy on physical activity and exercise, one of the ways it does that is by reducing energy spent on inflammation," says Pontzer. (See: How Exercise Can Improve Your Immune System)

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