Long Covid19NCT06214455

Intermittent Fasting and a No-Sugar Diet for Long COVID Symptoms

A study testing Low sugar diet and 10-12 hour eating window and Low sugar diet, 8 hour eating window and fasting in people with Long Covid19 and Long COVID, run by Pacific Northwest University of Health Sciences at 2 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

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). Read more about this study

Who is it for?: Ages 19 to 69 years
Conditions the study is for: Long Covid19, Long COVID
What is being tested?: Low sugar diet and 10-12 hour eating window and Low sugar diet, 8 hour eating window and fasting
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 77 participants
Where: 2 sitesUnited States
Study dates: 4 Nov 2022to 10 Sep 2024
Phase: Interventional
Are there results?: Yes, posted in the registrySummary in the doctors' view

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 19 to 69 years
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

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.

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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.

Who cannot join

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

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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

Trial locations and contacts

2 sites in 1 country.

United States2 sites

Remote trial - anyone residing in the United States
Boulder, Colorado, 80303
Pacific Northwest University
Yakima, Washington, 98901

Other trials in United States

About this study

Official title: The Effect of a No-added Sugar Diet, Time-restricted Eating and Periodic Water Fasting on Long COVID Symptoms

Read the detailed description

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.

Conditions: Long Covid19, Long COVID
Being tested: Low sugar diet and 10-12 hour eating window, Low sugar diet, 8 hour eating window and fasting
Keywords: COVID-19; fasting, diet
Medical subject headings: Post-Acute COVID-19 Syndrome, COVID-19, Fasting

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Low sugar diet and 10-12 hour eating windowOther
Low sugar diet and 10-12 hour eating window for four weeks
Low sugar diet, 8 hour eating window and fastingOther
Low sugar diet, 8 hour eating window and a 36-60 hour fast once per week for four weeks.

Study groups in NCT06214455
Study group	Role	What they receive
10-12 hour daily Time-Restricted Eating (4 weeks)	Active comparator	In this crossover trial, half the participants did the 10-hour TRE first (treatment A), half did it last. A no added sugar diet was suggested for the entire study. Receives: Other: Low sugar diet and 10-12 hour eating window
8-hour TRE, weekly 23 to 60 hour fast (4 weeks)	Experimental	Eating in an 8-hour window daily, with one 23-60 hour fast per week. A no-added sugar diet was suggested. Receives: Other: Low sugar diet, 8 hour eating window and fasting

What is being measured

The primary outcome is the main question the study is designed to answer.

Change in LC-Score, Per Treatment
This Outcome Measure is calculated by subtracting the Long COVID symptom severity score (LC-Score) before a treatment from the LC-Score after the treatment (i.e., score-after minus score-before). Negative values represent a reduction in number and severity of symptoms following treatment. LC-Scores are the sum of severity scores (0-4) for 28 common symptoms plus the count of 32 additional symptoms present. The maximum possible LC-Score is (28x4)+32 = 144.
Measured: Before and after 4 weeks of Fasting treatment or TRE treatment
Change in Number of Long COVID Symptoms, Per Treatment
This Outcome Measure is calculated by subtracting the Number of Long COVID symptoms (numLCsym) before a treatment from the numLCsym after the treatment (i.e., number-after minus number-before). Negative values represent a reduction in number of symptoms following treatment. The numLCsym is the count of 60 common symptoms.
Measured: Before and after 4 weeks of Fasting treatment or TRE treatment

Secondary outcomes (3)

Change in LC-Score, Overall
This Outcome Measure is calculated by subtracting the Long COVID symptom severity score (LC-Score) at baseline from the LC-Score after the final treatment (i.e., score-after minus score-before). Negative values represent a reduction in number and severity of symptoms following treatment. LC-Scores are the sum of severity scores (0-4) for 28 common symptoms plus the count of 32 additional symptoms present. The maximum possible LC-Score is (28x4)+32 = 144.
Measured: From enrollment to the end of the final treatment (10 weeks)
Change in Number of Long COVID Symptoms, Overall
This Outcome Measure is calculated by subtracting the Number of Long COVID symptoms (numLCsym) at baseline from the numLCsym after the final treatment (i.e., number-after minus number-before). Negative values represent a reduction in number of symptoms following treatment. The numLCsym is the count of 60 common symptoms.
Measured: From enrollment to the end of the final treatment (10 weeks)
Serious Adverse Events
Adverse events were medically reviewed and categorized as Serious if appropriate
Measured: During 4 weeks of Fasting treatment or during 6 weeks of TRE

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

4 Nov 202210 Sep 2024

First posted19 Jan 2024
Study start4 Nov 2022
Primary completion1 Jul 2024
Study completion10 Sep 2024

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Long Covid19Studies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase N/A
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Crossover
Model description: 2-week baseline period with adoption of no-sugar diet followed by treatment AB or treatment BA in a randomized crossover design.
Masking: Single blind
Who is masked: Outcomes assessor
Enrolment: 77 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06214455
Sponsor's protocol ID: 2022-06-PNWU
Status last verified: Apr 2026
First submitted: 3 Jan 2023
Last updated: 14 May 2026
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: No: No current plan to share data with other researchers.

Publications

Bunker T, Horne BD, Baldwin MD, Sorrells R, Turner S, Laube L, Solomon A, Horne LA, Novack J. Intermittent fasting and a no-sugar diet for Long COVID symptoms: a randomized crossover trial. Sci Rep. 2025 Jul 29;15(1):27563. doi: 10.1038/s41598-025-07461-0.
PubMed 40730806

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

See locations

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All Long Covid19 trials

Study at a glance

From the registry record, last updated by the sponsor on 14 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: The Effect of a No-added Sugar Diet, Time-restricted Eating and Periodic Water Fasting on Long COVID Symptoms
ClinicalTrials.gov ID: NCT06214455
Acronym / sponsor ID: 2022-06-PNWU
Conditions: Long Covid19, Long COVID
Keywords: COVID-19; fasting, diet
Study type: Interventional
Recruitment status: Completed
Enrolment: 77 participants (actual)
Lead sponsor: Pacific Northwest University of Health SciencesUniversity, hospital or other
Study start: 4 Nov 2022 (actual)
Primary completion: 1 Jul 2024 (actual)
Study completion: 10 Sep 2024 (actual)
First posted: 19 Jan 2024 (actual)
Results: Posted 14 May 2026

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Crossover
Masking: Single blind (outcomes assessor)
Number of arms: 2
Model description: 2-week baseline period with adoption of no-sugar diet followed by treatment AB or treatment BA in a randomized crossover design.

Arm	Type	Receives
10-12 hour daily Time-Restricted Eating (4 weeks)	Active comparator	Other: Low sugar diet and 10-12 hour eating windowIn this crossover trial, half the participants did the 10-hour TRE first (treatment A), half did it last. A no added sugar diet was suggested for the entire study.
8-hour TRE, weekly 23 to 60 hour fast (4 weeks)	Experimental	Other: Low sugar diet, 8 hour eating window and fastingEating in an 8-hour window daily, with one 23-60 hour fast per week. A no-added sugar diet was suggested.

Who may qualify

Ages: 19 to 69 years
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (13 listed)

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.

Key exclusion criteria (19 listed)

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

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Low sugar diet and 10-12 hour eating windowLow sugar diet and 10-12 hour eating window for four weeks	Other	10-12 hour daily Time-Restricted Eating (4 weeks)
Low sugar diet, 8 hour eating window and fastingLow sugar diet, 8 hour eating window and a 36-60 hour fast once per week for four weeks.	Other	8-hour TRE, weekly 23 to 60 hour fast (4 weeks)

Primary outcome

Change in LC-Score, Per Treatment
Time frame: Before and after 4 weeks of Fasting treatment or TRE treatment
This Outcome Measure is calculated by subtracting the Long COVID symptom severity score (LC-Score) before a treatment from the LC-Score after the treatment (i.e., score-after minus score-before). Negative values represent a reduction in number and severity of symptoms following treatment. LC-Scores are the sum of severity scores (0-4) for 28 common symptoms plus the count of 32 additional symptoms present. The maximum possible LC-Score is (28x4)+32 = 144.
Change in Number of Long COVID Symptoms, Per Treatment
Time frame: Before and after 4 weeks of Fasting treatment or TRE treatment
This Outcome Measure is calculated by subtracting the Number of Long COVID symptoms (numLCsym) before a treatment from the numLCsym after the treatment (i.e., number-after minus number-before). Negative values represent a reduction in number of symptoms following treatment. The numLCsym is the count of 60 common symptoms.

3 secondary outcomes

Change in LC-Score, Overall
Time frame: From enrollment to the end of the final treatment (10 weeks)
Change in Number of Long COVID Symptoms, Overall
Time frame: From enrollment to the end of the final treatment (10 weeks)
Serious Adverse Events
Time frame: During 4 weeks of Fasting treatment or during 6 weeks of TRE

Results and safety

Results posted to the registry on 14 May 2026, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
TRE Then Fasting	38	37
Fasting Then TRE	39	34

Primary outcome: Change in LC-Score, Per Treatment

Time frame: Before and after 4 weeks of Fasting treatment or TRE treatment. Mean (Standard Deviation). Unit: Scores on a Scale

Measure	Fasting 4 Weeks n = 58	TRE 4 Weeks n = 58
Value	-10.2 (13.6)	-2.8 (11.6)

Population analysed: Because this is a crossover trial, all participants did both treatments, one group did TRE then Fasting, the other group did Fasting then TRE. Only those participants that successfully completed the full trial and followed the protocol as designed are included.

Primary outcome: Change in Number of Long COVID Symptoms, Per Treatment

Time frame: Before and after 4 weeks of Fasting treatment or TRE treatment. Mean (Standard Deviation). Unit: Number of Symptoms

Measure	Fasting 4 Weeks n = 58	TRE 4 Weeks n = 58
Value	-5.0 (5.6)	-1.4 (4.8)

3 secondary outcomes are reported in the full results.

Adverse events

Time frame: From initial baseline symptom survey until completion of both treatments 10-weeks later.. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
2 Week Baseline	0 of 77 (0%)	11 of 77 (14.3%)	0 of 77
TRE Treatment	1 of 70 (1.4%)	19 of 70 (27.1%)	0 of 70
Fasting Treatment	1 of 66 (1.5%)	17 of 66 (25.8%)	0 of 66

Limitations and caveats (from the sponsor): 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.

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 14 May 2026.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Results publication: PubMed 40730806Bunker T, Horne BD, Baldwin MD, Sorrells R, Turner S, Laube L, Solomon A, Horne LA, Novack J. Intermittent fasting and a no-sugar diet for Long COVID symptoms: a randomized crossover trial. Sci Rep. 2025 Jul 29;15(1):27563. doi: 10.1038/s41598-025-07461-0.
Individual participant dataSharing planned: No. No current plan to share data with other researchers.

Related trials for Long Covid19

Not yet recruitingPhase 1
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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Jeffrey Novack, PhD principal investigator

Pacific Northwest University of Health Sciences

2 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 13 inclusion and 19 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 14 May 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 2 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

Yes. Results are posted in the registry (first posted 14 May 2026). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Change in LC-Score, Per Treatment (time frame: Before and after 4 weeks of Fasting treatment or TRE treatment). The study lists 2 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06214455, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 14 May 2026.