This cross-over study will assess a no added sugar diet, a restricted daily eating window, and one or two full day water fasts to determine if there is an effect on self-reported symptoms of Long Covid (PASC).

This remote study will use a cross-over design to test a diet change plus a 10-12 hour eating window (Treatment A) compared to a diet change, an 8-hour eating window, and one 36 or 60 hour fast per week (Treatment B). Both potential Treatment A and potential Treatment B are 4 weeks in duration. To be eligible, subjects must have a minimum of five common long COVID-19 symptoms. The fasting will limit food intake but not water intake. There will be a two-week run-in with weekly surveys of patient-reported symptoms and severity. The subjects will be randomly assigned to Group AB or to Group BA. Since the water fasts are at the beginning of the week (with symptoms surveyed at the end of the week) there is a 5-6 day washout and then a cross-over to the other treatment for Group BA. A Likert 0-4 scale is used to track the severity of 28 of the most common patient-reported symptoms each week. An additional 30 symptoms are also tracked. Subjects are asked to follow a no-added sugar diet for the entire 10 weeks of the study.

Inclusion Criteria

• Adult (18-69 years old)
• Five or more common Long Covid symptoms
• Free from fever > 100F and known bacterial and parasitic infections
• Must indicate willingness to limit certain supplements and report all medications.
• Must indicate willingness to make significant dietary changes - and limit daily eating to an 8 or 10 hour window.
• Must indicate willingness to attempt 36 hr or 60 hr water fasts each week for 4 weeks.
• Have a valid email address and phone number
• Reside in the United States
• Be able to read and to communicate in English
• Must indicate willingness to avoid "extra" supplements such as Fish Yes Oil, Cod liver Oil, Krill Oil, MCT oil, Coconut Oil, Tumeric/Curcumin, Berberine, Quercetin (> 500 mg), Red Yeast Rice, French Marine Bark extract, Red Sage, Ginko biloba, Oregano Oil, Peppermint Oil, Black seed oil, Cinnamon bark extract, Elderberry, Stinging Nettle, Milk Thistle, Monolaurin, Vendicinals 9, Tollovid, QuadraMune and all Probiotics.
• Must indicate willingness to avoid certain nutraceuticals such as Zinc (more than 25 mg), Arginine, Glutamine, Palmitoylethanolamide (PEA), Alpha Lipoic Acid, L Carnitine and Taurine during the study period.
• Must indicate willingness to avoid longevity supplements such as NAD+, Niacin, NMN, Nicotinamide Riboside, Spermidine and Fisetin during the study period.
• Must indicate willingness to halt Olive oil consumption greater than 1 tsp daily during the study period.

Exclusion Criteria:

• Likely COVID-19 or SARS-CoV-2 infection < 45 days before enrollment
• Body Mass Index (BMI) must be 20 or greater
• Past history of an eating disorder.
• Previously fasted more than 18 hours with Long COVID
• Currently doing intermittent fasting
• Pregnant or breast-feeding
• Severe pulmonary disease requiring supplemental oxygen
• Partial loss of vision due to macular degeneration
• Any recent (90 days) history of malignancies, fractures, surgery, radiation, chemo, anesthesia, or traumas
• Diagnosed with Type I or Type II Diabetes
• Previous Autoimmune condition
• Heart condition (Coronary artery disease, Heart valve disease, Heart No failure, Stroke)
• Pre-pandemic Arrythmia
• Liver disease
• Previous Chronic Health Conditions that did not fully resolve (Includes ME/CFS, Lyme Disease, and Fibromyalgia)
• Prescription anticoagulation medication that cannot be halted during the study period. Brilinta (ticagrelor), Plavix (clopidogrel), Coumadin, Warfarin etc.
• High Cholesterol medications that cannot be halted or reduced during the study period (Fenofibrate, Statins > 10 mg)
• Anti-inflammatories or immunosuppressants such as Steroids, Low dose Naltrexone (LDN), Maraviroc, Remicade/Infliximab or Colchicine that cannot be halted during the study period
• Metformin, Ivermectin, or peptides such as BCP-157 that cannot be halted during the study period

No current plan to share data with other researchers.

Only those participants that successfully completed the full trial and followed the protocol as designed are included.

From initial baseline symptom survey until completion of both treatments 10-weeks later.

Adverse events were captured via participant weekly symptom surveys. They were reviewed by the study doctor and classified as Serious or Other. Because many of the common symptoms of Long COVID are incapacitating, especially during flare-ups, serious adverse events were limited to those that required hospitalization or those that were considered medically serious upon review by the study doctor. Any unusual or concerning health event was tracked as an adverse event.

Limitations include no follow-up symptom surveys after the intervention period to assess the durability of patient gains. This trial relied on patient-reported symptoms and severity assessment since there are no available biomarkers for Long COVID. Finally, although subjects were excluded if they had a prior chronic health condition, changes in other factors not related to the fasting interventions may have impacted participant symptoms, which could bias outcomes.