Study shows regular fasting can lead to fewer hospitalizations and deaths from COVID-19

Benjamin Horne, director of cardiovascular and genetic epidemiology at Intermountain Healthcare, speaks at a press conference on Wednesday about a study which shows fasting can have a positive impact on COVID-19 outcomes. (Emily Ashcraft, KSL.com)

Estimated read time: 5-6 minutes

SALT LAKE CITY — For more than two years, many people have been trying to take steps to either prevent contracting COVID-19 or be able to fight the disease if they do catch it. Research by a Utah doctor found one more way people can help the disease from being serious is a habit many Utahns already have — fasting.

The Intermountain Healthcare study showed that a pattern of regular fasting over a period of several years leads to less severe complications from COVID-19, including reduced hospitalizations and deaths. The study was published on July 1 in BMJ Nutrition, Prevention & Health, a peer-reviewed publication.

Dr. Benjamin Horne, director of cardiovascular and genetic epidemiology at Intermountain Healthcare and principal investigator of the study, said regular time periods where a person does not consume any calories can benefit health in multiple ways, including the immune system.

“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 Horne.

Horne said fasting was previously found to reduce and metabolic risk factors for coronary disease, heart attacks and cardiovascular diabetes, partially because it can lead to weight loss, particularly during intense fasting regimens, but also due to biological mechanisms that are activated during a fast.

This can include fasting for 24 hours monthly, weekly or twice a week, or fasting for 16 hours a day and eating during an eight-hour period every day. In this study, it is unclear if a certain type of fasting is better than another at helping with COVID-19 recovery, although daily intermittent fasting doesn’t activate some beneficial mechanisms that are not associated with weight loss, according to Horne.

He said of the study’s participants who reported regularly fasting, the average length of time they had been fasting was over 40 years, with one participant reporting fasting for over 81 years.

Horne said many in Utah who fast regularly are members of The Church of Jesus Christ of Latter-day Saints who participate in a 24-hour fast once a month. He said about 40-45% of participants in the study who are members of the church reported fasting regularly, so members of the church were found in both groups. They considered about 36 other variables, including whether a person smokes or drinks alcohol, which members of the church are encouraged to avoid doing, to show that fasting was an independent factor linked to improved COVID-19 outcomes.

Horne, who has studied the health impacts of fasting in multiple other studies, has taken advantage of being in a state where 62% of people are members of the church and there is a higher-than-normal percentage of people who regularly fast.

The study was done in patients who enrolled in the INSPIRE registry, a voluntary health registry with Intermountain Healthcare, and tested positive for COVID-19 prior to Feb. 2021 when vaccines became widely available. It included 205 patients who tested positive for COVID-19, with 73 who said they practiced regular fasting.

“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,” Horne said.

He said they noticed some mechanisms associated with more positive COVID-19 effects can be caused by fasting, but researchers have not yet determined what the exact cause or causes of the improved outcomes are.


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. Benjamin Horne, principal investigator of the study


One theory is that mechanisms from fasting can combat respiratory failure from hyper inflammation, called cytokine storm, which can be the cause of some COVID-19 deaths. Fasting can also deactivate T cells, which are targeted by COVID-19, and activate other immune cells. Additionally, fasting can reduce the ability of COVID-19 to get into cells, especially when someone has a habit of fasting over multiple years.

Horne said he was not surprised by the results, although studies on fasting in the past have typically looked at chronic diseases rather than an acute infectious disease like COVID-19.

He said when human populations do not have immediate access to food, those who could still respond to infectious diseases when weakened from lack of food would survive — meaning, historically, humans have been able to protect against infection by fasting.

“Fasting is something that’s ingrained in our DNA. It’s inside of each one of us as a mechanism … that can be activated if you fast. And so people around the world, wherever they are, regardless of how much money they have, regardless of any of their personal characteristics — race, ethnicity, gender or so forth — everybody can fast,” Horne said.

He said fasting once a month would likely not help someone in the short term, but doing so a few times a week might.

The study did not address whether fasting after a COVID-19 diagnosis would be helpful in fighting the disease, and Horne suggested speaking with a dietician or doctor before beginning an intense fasting regimen and to consider what will be sustainable for the long term. Horne said fasting is generally safe but can be less safe for people with diabetes, people who are pregnant or lactating, and children.

Horne suggests this study is a “complementary finding” for reducing the severity of COVID-19, following multiple other therapies including vaccinations.

“It’s not feasible to vaccinate the entire world every six months with a COVID-19 vaccine. And so having a routine fasting regimen, that’s something that’s sustainable over a long period of time, is something that can potentially help people to fill in the gaps between the vaccination boosters so that you have some additional immunity to be able to protect yourself from the COVID-19 severity,” Horne said.

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Emily Ashcraft joined KSL.com as a reporter in 2021. She covers courts and legal affairs, as well as health, faith and religion news.

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