The Impact of a 48-hour Fast with or Without Exercise on Immune Cell Metabolism and Glycemic Control in Healthy Active Adults (FASTEX)

March 4, 2025 updated by: Jonathan Little, University of British Columbia

The Impact of a 48-hour Fast with or Without Exercise on Immune Cell Function, Bioenergetics, and Glycemic Control in Healthy Active Adults: a Randomized Crossover Trial

Many individuals engage in fasting for its purported health benefits but the effects of fasting on immune cell and whole body metabolism are not well understood in humans. Moreover, how exercising during a prolonged fast impacts immunometabolic outcomes is unclear. This study will determine how a 2 day fast - performed with or without daily exercise - impacts immune cell bioenergetics, immune cell function, and whole-body glycemic control in healthy active individuals.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Participants will perform two, 48-hour fasts separated by 5 days while wearing a continuous glucose monitor to measure glycemic responses. The order of the trials will be randomized for each participant. The two trials will include an exercise condition (FAST+EX) and a control, non-exercise condition (FAST). During the FAST+EX trial, participants will perform 60 minutes of cycling on each of the two days of the fast. Each bout of exercise will be 60 minutes in duration and consist of 50 minutes of cycling at 60% of predicted heart rate reserve (HRR) followed by 5 x 1-minute intervals at 90% of predicted HRR with 1-minute of passive recovery between each interval. During the FAST trial, participants will be asked to refrain from any structured exercise during the days of the fast. To start the trial, participants will arrive at the lab following an overnight fast. They will consume a standardized meal replacement (Ensure Plus Calories) and blood will be drawn 2 hours post-ingestion. Participants will come to the lab 24 and 48 hours later for subsequent blood draws prior to breaking their fast with the same standardized meal replacement. Another blood sample will be taken 2 hours post-prandial. Participants will be asked to replicate food consumption in each condition for the 24-hour period after they break their fast, and consume the same standardized meal replacement on the morning following the completion of each fast to measure free-living glycemic control 24-hours after a fast performed with or without exercise. There will be a five-day wash out period in between the completion of both trials for all participants.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
15

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Jonathan Little Principal Investigator, Professor Little, Ph.D
  • Phone Number: 250-807-9876
  • Email: jonathan.little@ubc.ca

Study Locations

  • Canada
    • British Columbia
      • Kelowna, British Columbia, Canada, V1V1V7
        • Recruiting
        • University of British Columbia Okanagan Campus
        • Contact:

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Aged between 19 and 35 years.
  • Physically active (engaging in ≥150 minutes of weekly moderate to vigorous physical activity).

Exclusion Criteria:

  • History of cardiometabolic diseases or inflammatory diseases (e.g., chronic obstructive pulmonary disease (COPD), rheumatoid arthritis, cardiovascular disease).
  • Individuals currently following a ketogenic diet, low-calorie diet, periodic fasting regimen, or consuming ketogenic supplements (e.g., exogenous ketone drinks).
  • Cigarette/vaping smoking.
  • Physical limitation that will impair the ability of the participant to perform exercise.
  • Individuals having a body mass index (BMI) over 30 kg/m2.
  • Cancer diagnosis in the past 5 years.
  • Taking anti-inflammatory drugs (e.g., ibuprofen, aspirin, naproxen).
  • Being unable to read or communicate in English.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Other
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Fasting + Exercise (FAST+EX): fasting + exercise condition
48-hour fast with 60 minutes of cycling on the first and second day of the fast.
Other: Fasting + Exercise (FAST+EX): fasting + exercise condition
Participants will complete a 48-hour fast. One hour of exercise will be performed on each morning of the fast.
Experimental: Fasting only (FAST): Non-exercise fasting condition
48-hour fast with no structured exercise on fasting days.
Other: Fasting only (FAST): Non-exercise fasting condition
Participant will complete a 48-hour fast. No structured exercise will be performed during each of the fasting days.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Monocyte mitochondrial respiration
Time Frame: Baseline and 48 hours
Mitochondrial respiration will be measured in primary human monocytes using high resolution respirometry before and after a 48-hour fast performed with or without exercise.
Baseline and 48 hours

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Alteration in immune cell functions
Time Frame: Baseline and 48 hours
Immune cell functions will be assessed with the combination of whole blood cultures treated with lipopolysaccharide (with or without interleukin-10) and the subsequent measurement of cytokine secretion, immune cell counts, and phenotyping via flow cytometry, both before and after 48 hours fast (with and without exercise).
Baseline and 48 hours
Change in glucose tolerance
Time Frame: Baseline, after 48 hours of fasting, and 24 hours after breaking the fast in free-living condition)
Investigate whether exercise performed during a 48-hour fast can reduce the temporary glucose intolerance typically seen after fasting, both in controlled and free-living conditions. Glucose tolerance will be evaluated by measuring capillary glucose levels before, and at 30, 60, and 120 minutes after a mixed meal tolerance test.
Baseline, after 48 hours of fasting, and 24 hours after breaking the fast in free-living condition)
Blood pressure
Time Frame: Baseline, 24 hours into the fast, and at the end of the fast (48 hours)
Systolic and diastolic blood pressure, as well as heart rate, will be measured using an automatic blood pressure device at baseline (Day 1), 24 hours into the fast (Day 2), and at the end of the 48-hour fast (Day 3) in both conditions (fasting alone and fasting with exercise).
Baseline, 24 hours into the fast, and at the end of the fast (48 hours)
Rate and level of ketosis
Time Frame: Baseline, 24 hours and 48 hours during fasting
Examine whether performing exercise at the beginning and during a fast can influence the ketone levels achieved after 24 and 48 hours of fasting. Capillary beta-hydroxybutyrate (a ketone body) will be measured via finger pricks using the Freestyle Neo ketone test.
Baseline, 24 hours and 48 hours during fasting
Compensatory movement behaviour
Time Frame: During and 48 hours after the fast
Explore whether adding exercise during fasting could intensify compensatory movement behaviors, as indicated by changes in sedentary behavior, light physical activity, and moderate to vigorous physical activity, measured using an accelerometer (ActivPAL).
During and 48 hours after the fast
Hunger sensation
Time Frame: At baseline, 12:00, 18:00 during the first and second day of the fast.
Hunger will be assessed using a 10-cm visual analogue scale at several time points: in the morning at the start of the fast, at 12:00 and 18:00 on the same day, at the same times the following day, and just before breaking the fast 48 hours later.
At baseline, 12:00, 18:00 during the first and second day of the fast.
Sleep quality
Time Frame: Baseline the morning before starting the fast, after 24 hours of fasting, and again after 48 hours of fasting.
Sleep quality will be assessed using a 10-cm visual analog scale based on the Richards-Campbell Sleep Questionnaire (2000). Measurements will be taken at baseline the morning before starting the fast, after 24 hours of fasting, and again after 48 hours of fasting.
Baseline the morning before starting the fast, after 24 hours of fasting, and again after 48 hours of fasting.
Affect during exercise
Time Frame: Before, during (e.g., at 10, 20, 30, 40, and 50 minutes as well as during intervals 1,2,3,4, and 5 at the end of the intervals as well as during the passive recovery) and following the two exercises conditions (post 5 minutes in a seated position).
The Feeling Scale (FS) developed by Hardy and Rejeski (Hardy & Rejeski, 1989) will be used to measure affective valence when exercise is performed in the fed (Baseline) and fasted state (24h fasted). Specifically, FS will be measured before, during (e.g., at 10, 20, 30, 40, and 50 minutes as well as during intervals 1,2,3,4, and 5 at the end of the intervals as well as during the passive recovery) and following the two exercises conditions (post 5 minutes in a seated position).
Before, during (e.g., at 10, 20, 30, 40, and 50 minutes as well as during intervals 1,2,3,4, and 5 at the end of the intervals as well as during the passive recovery) and following the two exercises conditions (post 5 minutes in a seated position).
Remembered Enjoyment
Time Frame: 10 minutes after each exercise session.
Remembered enjoyment will be measured with the original Physical Activity Enjoyment Scale (PACES; Kendzierski & DeCarlo, 1991) 10 minutes following each supervised exercise session (i.e., fed and fasted).
10 minutes after each exercise session.
Rate of perceived exertion
Time Frame: During both exercise sessions at 10, 20, 30, 40, and 50 minutes as well as during intervals 1, 2, 3, 4, and 5 at the end of the intervals.
Rate of perceived exertion will be measured during both exercise sessions (i.e., fed and fasted) at 10, 20, 30, 40, and 50 minutes as well as during intervals 1,2,3,4, and 5 at the end of the intervals.
During both exercise sessions at 10, 20, 30, 40, and 50 minutes as well as during intervals 1, 2, 3, 4, and 5 at the end of the intervals.
Glucose homeostasis
Time Frame: During and 24 hours after both condition
Glucose homeostasis will be evaluated using a continuous glucose monitor (Freestyle Libre 2, Abbott) under both conditions-fasting alone and fasting combined with exercise. Key markers of glucose homeostasis will be assessed based on Battelino et al. (2022; Lancet Diabetes Endocrinol), and will include average glucose levels, glycemic variability (SD), and time spent below (≤ 3.9 mmol/L), within (3.9-10.0 mmol/L), and above range (≥ 10.0 mmol/L).
During and 24 hours after both condition

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University of British Columbia

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
January 10, 2025

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
August 1, 2025

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
August 1, 2025

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
October 8, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
December 11, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
March 25, 2025

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
March 25, 2025

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
March 4, 2025

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
March 1, 2025

More Information

Terms related to this study

Keywords

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • H24-01732

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

IPD will not be shared to ensure the privacy and confidentiality of participants, in accordance with ethical guidelines and data protection regulations. Additionally, this was not included in the informed consent, which did not cover data sharing or address potential risks of re-identification.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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