Those who have regularly fasted intermittently for decades have a lower chance of being hospitalized or dying from COVID-19 compared to people who do not practice the eating plan, according to a new American study.
The small study, published July 1 in the peer-reviewed BMJ Nutrition, Prevention and Health, builds on previous research that examines the benefits of intermittent fasting.
Researchers looked at 205 patients who had tested positive for SARS-CoV-2, the virus that causes COVID-19, between March 2020 and February 2021 before vaccines were widely available. The patients who reported regularly fasting at least once a month for an average of 40 years or more had a lower rate of hospitalization or death from infection.
Patients were drawn from participants who signed up for a voluntary health registry at Intermountain Healthcare, a not-for-profit network of 33 hospitals based in Utah. Researchers chose this cohort specifically because of the large number of Mormons who live in the state. Members of the Church of Jesus Christ of Latter-day Saints typically do not eat or drink for two consecutive meals on the first Sunday of each month, according to the study.
Previous research suggests fasting not only helps burn fat, but offers health benefits as well. Studies have shown fasting can help control inflammation by reducing the amount of pro-inflammatory cells released into the blood. Fasting also triggers autophagy – a process by which the body breaks down and destroys old and damaged cells.
Fasting also switches its source of energy from glucose to fats and increases the amount of free fatty acids like linoleic acid circulating in the body.
While researchers said more work is needed to better understand why intermittent fasting is linked to better outcomes for COVID-19 patients, studies have shown severe cases of COVID-19 infection are typically associated with hyper-inflammation.
“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,” according to Dr. Benjamin Horne, the director of cardiovascular and genetic epidemiology at Intermountain Healthcare and lead co-author of the paper.
Horne noted that the patients in their study have been practicing intermittent fasting for decades, not just a few weeks, and said it is important that patients – particularly those who are older, pregnant, diabetic, or have heart and kidney diseases – talk with their family doctor first before trying it themselves.
The study found of the 205 patients with COVID-19, 11 per cent of those who fasted ended up hospitalized or died, compared to 28.8 per cent of patients who did not engage in the practice.
“This result was found in younger and older individuals, was present regardless of race or ethnicity, and did not depend on other cardiac risk factors, comorbidities or behaviours. Periodic fasting did not, however, predict whether or not a subject would be infected by SARS-CoV-2,” the authors wrote in the paper.
“Fasting remained significant in all multivariable analyses.”
Researchers also noted that prior to the availability of COVID-19 vaccines, Utah was one of only two U.S. states with a COVID-19 case fatality rate of less than one per cent. In addition, Utah had the lowest median age in the U.S. and was ranked as the state with the fourth lowest rate of coronary heart disease, according to the study.
“A low case fatality rate in Utah could also have occurred because the state has the lowest smoking rate in the U.S.A., has a limited racial/ethnic diversity…and had various healthcare system efforts that may have limited the severity of cases,” the paper said.
“Finally, Utah has the lowest per capita ethanol consumption in the U.S.A. that may have limited the spread of COVID-19 at bars and other social locales, but a connection of alcohol to COVID-19 severity is unconfirmed.”
The study said periodic fasting remained an independent predictor of a lower risk of hospitalization and mortality even after its analyses were adjusted for such factors including age, smoking, alcohol and ethnicity. The authors suggest the relatively higher rate of periodic fasting in Utah compared to other states may have contributed to the lower case fatality rates in the state.
“While fasting is not a panacea or a quick fix for health problems, low-frequency fasting improves cardiometabolic health even without significant weight loss, and multiple biological mechanisms and epidemiological results support the idea that consistent fasting may limit COVID-19 severity,” the study’s authors wrote.
Some of the limitations of the study include the observational nature of the study and there could be selection biases for participants who enrolled. The fasting history was also self-reported, which could result in imprecise data, the authors cautioned.
Researchers in the observational, longitudinal study – meaning patients were assessed over a period of time to detect any changes – stressed that intermittent fasting was not a substitute for vaccination, but that it could become a complementary therapy to vaccination.