COVID-19 Recovery and Intermittent Fasting: New Study Findings

Intermittent fasting alternates short fasts or significant calorie reduction with free eating. This trendy diet strategy may promote immunological function, weight control, and cardiovascular health. Because of these possible health benefits, people are beginning to research possible protective effects of this manner of eating on COVID-19 infection, hospitalization rates, and, hopefully, COVID-19 recovery. Let's take a closer look.

Intermittent fasting benefits: a comprehensive review

Intermittent fasting (IF) joins the many evolved food strategies to help people manage weight, assist with weight loss, and, theoretically, lessen one’s chance of developing obesity-related disorders, such as diabetes. IF is touted as having health benefits, from boosting and priming the immune system to potential cardiovascular benefits.

Intermittent fasting focuses not on what you eat but on when you eat. There is no standard duration for fasting or the number of meals to eat across research studies. This makes it hard to determine the right fasting duration and fully understand any complications or negative effects of this type of eating. Further, it is difficult to evaluate the benefits of IF in preventing or managing a specific disease or disease recovery state, such as COVID-19 recovery, due to the diversity of study protocols, fasting duration, and lack of research.

Basic intermittent fasting strategies

There are three basic eating strategies with IF. Still, there is no consensus on what is best, what creates the most likely health benefit, what factors enhance the immune system, or the ideal fasting duration before leading to malnutrition and negative energy balance.

1. Time-restricted eating. This is when one eats for only a specific number of hours per day and then fasts the rest of the day, e.g., eat from 7 a.m. until 2 p.m.
2. Extreme calorie restriction fasting or whole-day fasting. This is when a person fasts completely for one or two days a week or consumes only 25% of the daily needed calories. The rest of the week, the individual eats whatever they want. So someone may eat normally Wednesday through Sunday, then Monday and Tuesday, they consume only 400–500 calories the whole day. (Based on an average 2,000-calorie/day diet for the average adult).
3. Alternate-day fasting. This is when every other day one eats with no food restrictions, and then they consume only 25% of daily calories on the alternate days.

Suggested health benefits of intermittent fasting

Much of the human research to date is still very limited. It relies on animal data to establish the health benefits of IF practices.

It is difficult to review the data on IF because across studies, measured outcomes and types of studies differ, sample sizes are small or not generalizable to larger populations, and many other limitations exist. Thus, while some researchers report IF has health benefits, the science is less clear. In some individuals, weight loss and weight management can be achieved. The conducted research shows definite benefits and risks.

Intermittent fasting: pros and cons

Research is not conclusive about the actual health benefits. Some studies have suggested that IF has protective effects against heart disease, but others show no benefit.

In a 2021 Cochrane review, 26 studies were evaluated, which showed no significant changes in overall blood sugars or weight loss compared to other methods. Further, they found that studies about IF vary too much to assess long-term outcomes. These and other factors made any generalizations about protective effects on heart health and additional health outcomes infeasible.

These limitations hold true with other potential health benefit analyses, making it difficult to advise people with any certainty that IF is healthy and will be beneficial in preventing various negative health outcomes. In those 26 studies, mild headache was the only reported side effect consistently noted. Only one study evaluated quality of life, demonstrating a slight improvement in physical well-being.

Pros of intermittent fasting

Some research suggests that intermittent fasting and inflammation go hand in hand and that IF promotes a decrease in inflammation by various methods. Though science is still not clear, intermittent fasting benefits may include:

• Aiding in weight management or weight loss.
• Lessening one’s risk of heart disease.
• Improving our immune system’s resilience (ramping it up and helping it combat infections).
• Improving the immune system further by activating a cell surveillance system (autophagy), which helps the body remove damaged cells.
• Enhancing cellular resistance to stress.
• Decreasing inflammation when practiced in the long term.
• Reducing overall fat deposits over time (burning fat for energy).
• Improving the health of one's gut microbiome by reducing harmful byproducts created by unhealthy bacteria (a significant part of our immune system is located in the gut).
• Lowering one’s risk of metabolic diseases, such as diabetes.
• Improving circadian rhythm (biological clock).

Fasting and immune system benefits are most commonly noted, which may have special benefits in COVID-19 recovery. But remember, more human research is needed to determine IF’s benefits as studies are limited, and little research exists on long-term results.

Cons of intermittent fasting

What research has helped identify are possible negative outcomes as a result of IF practices. Further, there are some contraindications to following this type of diet.

• IF is a form of disorganized (disordered) eating, and it is not recommended for those with eating disorders.
• IF should not be undertaken without the supervision of a medical professional.
• Fasting can cause some people to become light-headed and even develop headaches.
• Fasting can negatively impact those who participate in regular exercise.
• It is contraindicated in those who are pregnant or nursing.
• It is not intended for children under 18.
• It is not appropriate for those with diabetes.
• It is not appropriate for those who are immunocompromised, such as those with cancer or immune-mediated diseases.
• Those practicing IF have the potential to develop nutritional deficiencies.

Because data is still lacking on IF, exact side effects or complications are not yet well known and are still being researched.

Fasting strategies for post-COVID-19 wellness

Could intermittent fasting help those recovering from COVID-19? Can it improve health symptoms experienced with long-COVID syndrome? Currently, the data is limited, and we cannot make this recommendation.

To evaluate the possible benefits of IF on COVID-19 impacts, not specifically on COVID-19 recovery, researchers performed an observational study, a less impactful study design than a randomized control trial. Participants were selected from the INSPIRE registry, a database that collects biological samples from healthy and ill individuals, such as blood, lab results, and other medical information. For this study, data was taken from 2013 to March 2020. They cross-referenced those in the registry with those tested for COVID. They reviewed outcomes for hospitalized patients in the Utah and SE Idaho regions.

This study evaluated those who fasted for more than five years before being diagnosed with COVID-19 and those who didn’t fast or fasted for short periods, such as for religious practices (once a month, for example). The study did not evaluate individuals using IF to recover from COVID-19 infections; it is solely based on outcomes from datasets.

It's important to mention that this research provides no scientific evidence to support or suggest that IF will decrease the immune response, improve immune function, or prevent long-term COVID-19 health impacts. It simply showed that those in the population evaluated with a history of IF of long duration had better COVID-19 outcomes (fewer hospitalizations or post-COVID-related concerns) than those who didn’t have a history of IF.

One final thing to remember when evaluating this single study is that these results were pre-vaccination development. Would the results be the same if this study were re-evaluated using data post-vaccination? If not, then that would suggest that IF may not be as beneficial as researchers hoped.

The potential link between fasting and COVID-19

When we fast, the body produces ketones instead of glucose to generate energy. This process leads to an increase in different fatty acids, including linoleic acid, as indicated by scientific studies.

In COVID-19, scientists discovered that the spike protein, targeted by mRNA vaccines, e.g., Pfizer's, strongly interacts with a fatty acid, reducing the virus's binding to a key human enzyme, ACE2. This binding allows the virus to enter human cells. Some researchers believe fasting-induced higher production of this acid might protect against COVID-19 infections by limiting the virus particles or infected cells. However, research on this is still in the early stages.

Much further research is needed to determine if IF truly has any long-term benefits for COVID-19-related issues. In this single study, results suggest potential benefits, and scientists recommend additional studies to evaluate the benefits of IF on COVID-19 infections, prevention of severe disease, and the recovery phase.

Should I fast to recover from COVID-19?

Post-COVID health strategies vary from one individual to another. Speak with a healthcare provider if you have suffered from COVID-19 and are having symptoms, such as brain fog, fatigue, new GI problems, new aches and pains, or other issues, and determine what strategies may help you.

IF may be beneficial in reducing inflammation, improving heart and overall health outcomes, and may help prevent complications or severe cases of COVID-19. However, current human research is still too new and insufficient, and more research is needed. While IF may have health benefits, it isn’t for everyone, and embarking on an IF journey should be done only under the care of a licensed healthcare provider.