Trial Outcomes & Findings for Intermittent Fasting and a No-Sugar Diet for Long COVID Symptoms (NCT NCT06214455)

Results Overview

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.

Recruitment status

COMPLETED

Study phase

NA

Target enrollment

77 participants

Primary outcome timeframe

Before and after 4 weeks of Fasting treatment or TRE treatment

Results posted on

2026-05-14

Participant Flow

Between November 2022 and April 2024, a total of 424 individuals were prescreened via pragmatic electronic means. Of these, 105 proceeded to screening and enrollment via video interview and consenting. A total of 77 participants enrolled and began a treatment arm.

Participants were randomly assigned to do treatment A then Treatment B ( Group AB) or to do Treatment B then Treatment A (Group BA). All participants first did a two-week baseline of 10-12 hr TRE before beginning the two four week treatment periods.

Participant milestones

Participant milestones
Measure	TRE Then Fasting Group AB did treatment A for 4 weeks followed by treatment B for 4 weeks. Treatment A (hereafter called TRE) was a no-sugar diet with a 10-12 hour daily TRE eating window. Treatment B (hereafter called Fasting) was the same no-sugar diet with a more restrictive 8-hour daily TRE eating window (and 16 consecutive hours of not eating), along with a once weekly 23-60 h water-only fast.	Fasting Then TRE Group BA did treatment B for 4 weeks followed by treatment A for 4 weeks. Treatment B (hereafter called Fasting) was the same no-sugar diet with a more restrictive 8-hour daily TRE eating window (and 16 consecutive hours of not eating), along with a once weekly 23-60 h water-only fast. Treatment A (hereafter called TRE) was a no-sugar diet with a 10-12 hour daily TRE eating window.
Baseline (2 weeks) STARTED	38	39
Baseline (2 weeks) COMPLETED	37	34
Baseline (2 weeks) NOT COMPLETED	1	5
First Intervention (4 weeks) STARTED	37	34
First Intervention (4 weeks) COMPLETED	32	33
First Intervention (4 weeks) NOT COMPLETED	5	1
2nd Intervention (4 weeks) STARTED	32	33
2nd Intervention (4 weeks) COMPLETED	29	29
2nd Intervention (4 weeks) NOT COMPLETED	3	4

Reasons for withdrawal

Withdrawal data not reported

Baseline Characteristics

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

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	TRE Then Fasting n=29 Participants Group AB did A for 4 weeks followed by treatment B for 4 weeks. Treatment A (hereafter called TRE) was a no-sugar diet with a 10-12 hour daily TRE eating window. Treatment B (hereafter called Fasting) was the same no-sugar diet with a more restrictive 8-hour daily TRE eating window (and 16 consecutive hours of not eating), along with a once weekly 23-60 h water-only fast.	Fasting Then TRE n=29 Participants Group BA did treatment B for 4 weeks followed by treatment A for 4 weeks. Treatment B (hereafter called Fasting) was the same no-sugar diet with a more restrictive 8-hour daily TRE eating window (and 16 consecutive hours of not eating), along with a once weekly 23-60 h water-only fast. Treatment A (hereafter called TRE) was a no-sugar diet with a 10-12 hour daily TRE eating window.	Total n=58 Participants Total of all reporting groups
Age, Continuous	50.2 Years STANDARD_DEVIATION 11.3 • n=1512 Participants	48.7 Years STANDARD_DEVIATION 10.8 • n=504 Participants	49.4 Years STANDARD_DEVIATION 11.1 • n=2016 Participants
Sex: Female, Male Female	20 Participants n=1512 Participants	22 Participants n=504 Participants	42 Participants n=2016 Participants
Sex: Female, Male Male	9 Participants n=1512 Participants	7 Participants n=504 Participants	16 Participants n=2016 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	1 Participants n=1512 Participants	0 Participants n=504 Participants	1 Participants n=2016 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	28 Participants n=1512 Participants	29 Participants n=504 Participants	57 Participants n=2016 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=1512 Participants	0 Participants n=504 Participants	0 Participants n=2016 Participants
Long COVID Score (LC-Score)	39.8 Scores on a Scale STANDARD_DEVIATION 17.9 • n=1512 Participants	35.9 Scores on a Scale STANDARD_DEVIATION 20.8 • n=504 Participants	35.9 Scores on a Scale STANDARD_DEVIATION 19.9 • n=2016 Participants
Number of Long COVID symptoms (numLCsym)	21.4 Number of Symptoms STANDARD_DEVIATION 9.0 • n=1512 Participants	19.6 Number of Symptoms STANDARD_DEVIATION 7.4 • n=504 Participants	20.5 Number of Symptoms STANDARD_DEVIATION 8.2 • n=2016 Participants
Duration of Long COVID symptoms	25.2 Months STANDARD_DEVIATION 10.9 • n=1512 Participants	23.9 Months STANDARD_DEVIATION 10.5 • n=504 Participants	24.6 Months STANDARD_DEVIATION 10.7 • n=2016 Participants

PRIMARY outcome

Timeframe: Before and after 4 weeks of Fasting treatment or TRE treatment

Population: 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.

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.

Outcome measures

Outcome measures
Measure	Fasting 4 Weeks n=58 Participants 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week. Because this is a crossover trial, the change in the Fasting treatment 4 weeks compared to the change in the TRE treatment 4 weeks was compared for all members of the analytic group.	TRE 4 Weeks n=58 Participants Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.
Change in LC-Score, Per Treatment	-10.2 Scores on a Scale Standard Deviation 13.6	-2.8 Scores on a Scale Standard Deviation 11.6

PRIMARY outcome

Timeframe: Before and after 4 weeks of Fasting treatment or TRE treatment

Population: 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.

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.

Outcome measures

Outcome measures
Measure	Fasting 4 Weeks n=58 Participants 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week. Because this is a crossover trial, the change in the Fasting treatment 4 weeks compared to the change in the TRE treatment 4 weeks was compared for all members of the analytic group.	TRE 4 Weeks n=58 Participants Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.
Change in Number of Long COVID Symptoms, Per Treatment	-5.0 Number of Symptoms Standard Deviation 5.6	-1.4 Number of Symptoms Standard Deviation 4.8

SECONDARY outcome

Timeframe: From enrollment to the end of the final treatment (10 weeks)

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.

Outcome measures

Outcome measures
Measure	Fasting 4 Weeks n=58 Participants 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week. Because this is a crossover trial, the change in the Fasting treatment 4 weeks compared to the change in the TRE treatment 4 weeks was compared for all members of the analytic group.	TRE 4 Weeks Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.
Change in LC-Score, Overall	-19.6 Scores on a Scale Standard Deviation 16.3	—

SECONDARY outcome

Timeframe: From enrollment to the end of the final treatment (10 weeks)

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.

Outcome measures

Outcome measures
Measure	Fasting 4 Weeks n=58 Participants 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week. Because this is a crossover trial, the change in the Fasting treatment 4 weeks compared to the change in the TRE treatment 4 weeks was compared for all members of the analytic group.	TRE 4 Weeks Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.
Change in Number of Long COVID Symptoms, Overall	-8.3 Number of Symptoms Standard Deviation 9.24	—

SECONDARY outcome

Timeframe: During 4 weeks of Fasting treatment or during 6 weeks of TRE

Population: Adverse events were tracked for all trial participants, not just the final analytic group of 58

Adverse events were medically reviewed and categorized as Serious if appropriate

Outcome measures

Outcome measures
Measure	Fasting 4 Weeks n=77 Participants 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week. Because this is a crossover trial, the change in the Fasting treatment 4 weeks compared to the change in the TRE treatment 4 weeks was compared for all members of the analytic group.	TRE 4 Weeks n=66 Participants Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.
Serious Adverse Events	1 Number of Serious Adverse Events	1 Number of Serious Adverse Events

Adverse Events

2 Week Baseline

Serious events: 0 serious events

Other events: 11 other events

Deaths: 0 deaths

TRE Treatment

Serious events: 1 serious events

Other events: 19 other events

Deaths: 0 deaths

Fasting Treatment

Serious events: 1 serious events

Other events: 17 other events

Deaths: 0 deaths

Serious adverse events

Serious adverse events
Measure	2 Week Baseline n=77 participants at risk All 77 participants that began the trial. Participants followed a no-sugar diet and 10-12 hour time-restricted eating for the baseline 2-week period.	TRE Treatment n=70 participants at risk All participants that began their 4-week TRE treatment period. Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.	Fasting Treatment n=66 participants at risk All participants that began their 4-week Fasting treatment period. 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week.
Gastrointestinal disorders acute appendicitis	0.00% 0/77 • 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.	1.4% 1/70 • 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.	0.00% 0/66 • 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.
Musculoskeletal and connective tissue disorders pleurisy, tendonitis	0.00% 0/77 • 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.	0.00% 0/70 • 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.	1.5% 1/66 • 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.

Other adverse events

Other adverse events
Measure	2 Week Baseline n=77 participants at risk All 77 participants that began the trial. Participants followed a no-sugar diet and 10-12 hour time-restricted eating for the baseline 2-week period.	TRE Treatment n=70 participants at risk All participants that began their 4-week TRE treatment period. Time-Restricted Eating for 10 -12 hours per day with a no added sugar diet.	Fasting Treatment n=66 participants at risk All participants that began their 4-week Fasting treatment period. 4 weeks of eating in an 8 hour window per day, with a no added sugar diet and a night-day-night water fast once per week.
General disorders Long COVID flare-up symptoms	5.2% 4/77 • 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.	11.4% 8/70 • 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.	16.7% 11/66 • 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.
General disorders Viral infection (Flu or COVID-19)	0.00% 0/77 • 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.	4.3% 3/70 • 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.	3.0% 2/66 • 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.
General disorders Vaccination reaction	2.6% 2/77 • 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.	1.4% 1/70 • 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.	0.00% 0/66 • 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.
Cardiac disorders Tachycardia or Chest pains	1.3% 1/77 • 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.	7.1% 5/70 • 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.	1.5% 1/66 • 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.
Gastrointestinal disorders Diarrhea	3.9% 3/77 • 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.	1.4% 1/70 • 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.	1.5% 1/66 • 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.
Respiratory, thoracic and mediastinal disorders Shortness of breath	0.00% 0/77 • 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.	1.4% 1/70 • 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.	0.00% 0/66 • 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.
Gastrointestinal disorders Vomiting	1.3% 1/77 • 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.	0.00% 0/70 • 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.	3.0% 2/66 • 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.

Additional Information

Jeffery Novack

Pacific Northwest University of Health Sciences

Phone: 2063693967

Email: [email protected]

Results disclosure agreements

Principal investigator is a sponsor employee
Publication restrictions are in place