Fasting and Long COVID

Fasting and Long COVID

Undertaking the ProLon Fasting Mimicking Diet (FMD) during COVID has not been tested so we have no data and can therefore not recommend ProLon during an active case of COVID. Likewise, we have no data guiding a decision to abort the FMD if the user develops symptoms or tests positive for COVID while on the FMD programme. The user should seek advice from a doctor or allied healthcare provider.

A 2016 study in mice found that glucose has different effects on bacterial and viral infections. Fasting may help fight off bacterial infections. The same research also indicate that consuming glucose, or sugar, may help combat viral infections [1]. In mice with a bacterial infection, glucose had a negative effect, but in those with a viral infection, the effect was positive. Because the common cold is a viral infection, the positive effect of glucose may help explain the adage, “Feed a cold, starve a fever.”

During fasting, blood sugar levels fall, and ketone levels rise. When the body has no more energy stores of glucose, it starts using amino acids and fat as energy sources. Using fat as fuel causes the body to produce ketones. Certain ketones, such as beta-hydroxybutyrate, may benefit the immune system.

Other research has also suggested that fasting may enable the body to regenerate healthy immune cells.

Post-viral complication is a well-documented phenomenon e.g. following glandular fever and Lyme disease. Symptoms of long COVID can last for weeks or sometimes months, and include: extreme fatigue (tiredness) shortness of breath, heart palpitations, chest pain or tightness.

It is possible that intermittent fasting may have beneficial effects on haemostatic risk markers for cardiovascular diseases [2].

ProLon FMD has not been tested as an intervention for Long COVID, so we can’t make any recommendations. The decision to use of ProLon for Long COVID should be made in consultation with a healthcare professional.

Therapeutic success of fasting in patients with Long COVID

In this video, Dr. Françoise Wilhelmi de Toledo and Dr. Eva Lischka describe four cases of former patients with long Covid symptoms, who experienced an impressive recovery after fasting in their clinic in Germany.


  1. Wang A, Huen SC, Luan HH, et al. Opposing Effects of Fasting Metabolism on Tissue Tolerance in Bacterial and Viral Inflammation. Cell. 2016;166(6):1512-25.e12.
  2. Aksungar FB, Eren A, Ure S, Teskin O, Ates G. Effects of intermittent fasting on serum lipid levels, coagulation status and plasma homocysteine levels. Ann Nutr Metab. 2005;49(2):77-82.