People who practice intermittent fasting experience less severe complications from COVID-19, study finds

In a new study published this week in BMJ Nutrition, Prevention & Health, Intermountain researchers found that COVID-19 patients who practiced regular water-only intermittent fasting had lower risk of hospitalization or dying due to the virus than patients who did not.

"Intermittent fasting has already shown to lower inflammation and improve cardiovascular health. In this study, we're finding additional benefits when it comes to battling an infection of COVID-19 in patients who have been fasting for decades," said Benjamin Horne, PhD, director of cardiovascular and genetic epidemiology at Intermountain Healthcare.

In the Intermountain study, researchers identified patients enrolled in the INSPIRE registry, a voluntary health registry at Intermountain Healthcare, who had also tested positive for SARS-CoV-2 between March 2020 and February 2021 -- before vaccines were widely available.

They identified 205 patients who had tested positive for the virus. Of those, 73 said they regularly fasted at least once a month. Researchers found that those who practiced regular fasting had a lower rate of hospitalization or death due to coronavirus.

"Intermittent fasting was not associated with whether or not someone tested positive COVID-19, but it was associated with lower severity once patients had tested positive for it," Dr. Horne said.

In the Intermountain study, participants who said they regularly fasted did so for an average of more than 40 years. Intermountain researchers had the opportunity to closely study this specific cohort of long-time intermittent fasters because a large portion of its patients fast regularly for religious reasons.

Nearly 62 percent of Utah's population belongs the Church of Jesus Christ of Latter-day Saints, whose members typically fast the first Sunday of the month by going without food or drink for two consecutive meals.

While Dr. Horne said that more research is needed to understand why intermittent fasting is associated with better COVID-19 outcomes, he said it's most likely due to a host of ways that it affects the body.

For example, fasting reduces inflammation, especially since hyperinflammation is associated with poor COVID-19 outcomes. In addition, after 12 to 14 hours of fasting, the body switches from using glucose in the blood to ketones, including linoleic acid.

"There's a pocket on the surface of SARS-CoV-2 that linoleic acid fits into -- and can make the virus less able to attach to other cells," he said.

Another potential benefit is that intermittent fasting promotes autophagy, which is "the body's recycling system that helps your body destroy and recycle damaged and infected cells," Dr. Horne added.

Dr. Horne stressed that these results are from people who have been practicing intermittent fasting for decades -- not weeks -- and that anyone who wants to consider the practice should consult their doctors first, especially if they are elderly, pregnant, or have conditions like diabetes, heart, or kidney disease.

Researchers also stressed intermittent fasting shouldn't be seen as a substitute for COVID vaccination.

"It should be further evaluated for potential short and long-term preventative or therapeutic use as a complementary approach to vaccines and anti-viral therapies for reducing COVID-19 severity," Dr. Horne said.