Effect of Early Time-Restricted Eating on Appetite, Appetite-Regulatory Hormones and Energy Intake

April 13, 2026 updated by: James Dorling, PhD, University of Glasgow

Effect of One Day Early Time-Restricted Eating (eTRE) on Appetite, Appetite-Regulatory Hormones and Energy Intake in Healthy Men Without Obesity

This randomised crossover study's primary aim is to investigate the effect of short-term fasting (eTRE) on subjective appetite and appetite-regulatory hormones (i.e., leptin, adiponectin, total glucagon-like peptide-1 (GLP-1), gastric inhibitory polypeptide (GIP), total peptide YY (PYY), acylated ghrelin and Insulin). In addition, to examine if the one-day early time-restricted eating influences energy expenditure and ad libitum energy intake in the periods following the standard meal test. The researchers will compare normal eating with early Time-Restricted Eating (eTRE) in healthy men.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet 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

Screening visit At the screening visit, the participant will firstly meet with a researcher involved in the study. They will then be directed to the laboratory before being asked to sign the informed consent form followed by the Health Screening questionnaire. Further, participants will have height and weight measured by a researcher, and BMI will be subsequently calculated. Those who are eligible to participate will be enrolled in the trial and will be invited for two experimental trials.

Those participants who are eligible will be asked to complete the International Physical Activity Questionnaire, to assess physical activity levels, a food preferences scale to examine how much they like the foods provided during experimental trials, and (should participants be eligible) participants will be provided with a food diary and scales that they must complete the day before their first and second experimental trials. Detailed instructions will be provided to participants on how to appropriately complete the food diary using the food scales.

Before experimental trials Participants will be instructed to complete two primary tasks prior to the experimental trials. First, participants will complete or follow a food diary. Specifically, 24 hours before the 2-day experimental trials, participants will complete a food diary, weighing and recording all food and beverage consumption. This is to ensure food and beverage intake is standardised in the 24 hours before the first experimental trial. Participants will also be instructed to fast from 20:30 the night before experimental trials.

Experimental trials Day 1 Participants will attend the lab at approximately 08:00 am. Participants will be fasting from 20:30 from the previous night (i.e., 12 hours without food or drink, except water). Once participants arrive, their weight will be recorded by a researcher, and they will rest until 09:00.

Normal diet In the normal diet experimental trial, the researcher will provide the standardised breakfast meal to participants at approximately 9:00 am. They will have 30 minutes to consume the meal. After this, participants will then rest in the metabolic research unit for the remaining 5.5 hours of the trial and will be allowed to work on laptops/tablets and relax in the metabolic research unit at the end of the trial (approximately 15:00; 7-hour trial in total), following a period of rest, they will then, at approximately 15:00, they will consume a standardised lunch, which they will have 30 minutes to consume. They will collect the standardised dinner to consume at home between 20:00 and 21.00 pm.

eTRE diet While in the eTRE diet experimental trial, they will consume the same meals but within a shorter time frame of six hours (9:00-15:00). The researcher will provide the standardised breakfast meal to participants at approximately 9:00 am. They will have 30 minutes to consume the meal. After this, participants will then rest in the metabolic research unit for the remaining 5.5 hours of the trial and will be allowed to work on laptops/tablets and relax in the metabolic research unit. Following a period of rest, they will then, at approximately 12:00 pm, they will consume a standardised lunch, which they will again have 30 minutes to consume. After this, participants will then rest in the metabolic research unit for the remaining 2.5 hours of the trial and will be allowed to work on laptops/tablets and relax in the metabolic research unit at the end of the trial (approximately 15:00; 7-hour trial in total), following a period of rest, they will then, at approximately 15:00 pm, they will consume a standardised dinner, which they will also have 30 minutes to consume. Water will be provided whenever the participant wishes. A researcher will be on hand to supervise the participant in the laboratory and will answer any questions the participant has.

The iVAS questionnaire will be administered to participants during the experimental trials (Normal/eTRE), which will take place seven times over a two-hour period. four of the questionnaires will be completed in the lab, while three will be taken home to fill out independently.

The design of the study is randomised and counter-balanced; half of the participants will complete the normal diet first, while the other half will complete the eTRE diet first.

Day 2 On the second day of the experimental trials, participants will arrive at the laboratory at approximately 08:00 having fasted (participants instructed not to eat or drink [except water] since 21:00 from the night of the normal diet experimental day and since 16:00 of the eTRE diet experimental day). A researcher trained in phlebotomy will insert a cannula into the antecubital vein. After about one hour to acclimatise to the cannula, a fasting blood sample will be collected, and data collection will begin.

Blood samples will be collected at various points. The investigators will first draw approximately 2 ml of excess blood and saline for each blood sample that may remain in the cannula. Following this, the investigators will withdraw 11.7 ml of blood for testing.

After the collection of each blood sample, measurements of the volume of oxygen consumed (V̇O2) and the volume of carbon dioxide produced (V̇CO2) will be recorded every 30 seconds for a total duration of 10-15 minutes. This will be achieved by the computerised open-circuit ventilated hood system (Quark RMR®, COSMED, Italy). Participants will be asked to lie supine and still. Once comfortable, a clear plastic canopy will be placed over the participant's head, and V̇O2 and V̇CO2 will be recorded every 30 seconds. Measurement values will be used to calculate the rate of fat and carbohydrate oxidation and the thermic effect of food through the tests. Volume and gas calibrations of the apparatus will be performed before measurement.

Participants will have a standardised breakfast (mixed meal tolerance test [1500 kcal]), consisting of croissants, butter, and milkshake.

Additionally, participants will be provided with an ad libitum buffet lunch in a private dining room under researcher supervision, as well as an ad libitum buffet dinner to take home and consume before going to bed. The lunch meal will include white and brown bread, butter, wafer chicken, mixed salad, yogurt, apples, bananas, muffins, and wine gums. The dinner meal will feature chicken, white and brown bread, cheese, butter, yogurt, nuts or granola, milk, chocolate chip cookies, apples and bananas. Participants will attend the laboratory for a supervised ad libitum buffet lunch. They will be seated individually and given a maximum of 30 minutes to consume the meal. All foods will be weighed before and after consumption to determine total energy intake. This lunch meal serves as the primary measure of energy intake in the study. More than enough items will be provided for the expected consumption, and if participants need more food items, they will be given them upon request. In addition, in the dinner meal, participants will be provided with ad libitum buffet takeaway dinner. They will be instructed to consume as much or as little of this meal as they wish, at any time before going to bed. It is important to inform them that they are not allowed to eat any of our foods for breakfast, the morning after Day 2. To determine the amount of each food item consumed, the investigators will measure the difference in weight between before and after the meal. The investigators will also use manufacturer details to determine energy and macronutrient consumption. Participants will return all remaining food packaging and containers the following day or by pre-arranged collection.

During this, appetite ratings (hunger, satisfaction, fullness, prospective food consumption and desire to eat) will be assessed using 100 mm Visual analogue scales (iVAS) at baseline, 0.5, 1, 2, 3, 4 and 5 hours. Additionally, a scale will be provided before and after the buffet dinner, resulting in a total of nine assessments. These scales are 100 mm long, with words anchored at each end expressing the most extreme appetite sensations.

Participants will then rest in the metabolic research unit, and they will be able to consume water ad libitum and will be able to bring laptops/tablets and books.

Finally, participants will be provided with the food diary they completed before the experimental trials (i.e., normal diet day and eTRE diet day) and the food scales.

In between 2-day experimental trials On the day before their experimental trials (i.e., normal diet day and eTRE diet day), participants will be asked to follow the food diary they completed 24 hours prior to each trial. They will also be instructed to fast from 8:30 PM the night before the experimental trials (i.e., no food or drink, except water, after 20:30). On the second day of the experimental trials. Participants should not eat or drink (except for water) after 9:00 pm the night of the normal diet experimental day and since 16:00 of the eTRE diet experimental day). Additionally, participants will be instructed to maintain their usual diet and daily routine and not to introduce any dietary changes or alterations to their routine that might affect appetite or appetite-related hormone responses. Participants will have the opportunity to contact the researcher at any point if they have questions.

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.
12

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.

Study Contact Backup

Study Locations

  • United Kingdom
      • Glasgow, United Kingdom, G31 2ER
        • New Lister Building at Glasgow Royal Infirmary Glasgow, United Kingdom G31 2ER

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
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Males aged 18 years or older.
  • BMI between 18.5 and 24.9 kg/m²
  • Have stable body mass for at least three months (within ±2 kg).

Exclusion Criteria:

  • Females
  • People who are younger than 18 or older than 65 years old.
  • Following a special diet (e.g. weight loss, vegetarian or vegan, etc.).
  • Have food allergies related to the study.
  • Smoking.
  • Taking any medications.
  • Suffering from metabolic health issues, e.g., history of diabetes, cardiovascular disease, or eating disorders.

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: Prevention
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

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: The normal diet experimental trial
The participants will attend the lab in a fast state. They will have three meals in 12 hours, each providing 33% of their estimated energy needs.
Other: instantaneous visual analogue scale (iVAS)
Appetite ratings (hunger, satisfaction, fullness, prospective food consumption and desire to eat) will be measured by visual analogue scales (VAS).
Dietary supplement: Normal diet
The participants will consume three meals in 12 hours, each providing 33% of their estimated energy needs.
Experimental: The eTRE diet experimental trial
The participants will attend the lab in a fast state. They will have three meals in 16 hours, each providing 33% of their estimated energy needs.
Other: instantaneous visual analogue scale (iVAS)
Appetite ratings (hunger, satisfaction, fullness, prospective food consumption and desire to eat) will be measured by visual analogue scales (VAS).
Dietary supplement: early Time-Restricted Eating (eTRE)
The participants will consume three meals in 6 hours, each providing 33% of their estimated energy needs.

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
Change in subjective appetite sensations
Time Frame: Will take place seven times over a two-hour period in Day1 and nine times in Day2 at 0 (baseline), 0.5, 1, 2, 3, 4, 5, 6 and 7 hours.
The researchers will assess the subjective appetite sensations using 100 mm visual analog scales (VAS) to measure appetite sensations (hunger, satiety, fullness, prospective food consumption, and desire to eat). The VAS are 100 mm long, with words anchored at each end expressing the most positive and negative ratings. Scores for each appetite construct range from 0-100.
Will take place seven times over a two-hour period in Day1 and nine times in Day2 at 0 (baseline), 0.5, 1, 2, 3, 4, 5, 6 and 7 hours.
Change in Total Peptide-YY (PYY)
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial, to measure the change in PYY levels. The area under the plasma concentration versus time curve (AUC) of PYY will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Acylated Ghrelin
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure changes in acylated ghrelin levels. The area under the plasma concentration versus time curve (AUC) of acylated ghrelin will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Glucagon-Like Peptide-1 (GLP-1)
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure the change in GLP-1 blood levels. Area under the plasma concentration versus time curve (AUC) of GLP-1 will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Leptin
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure the change in Leptin levels. The area under the plasma concentration versus time curve (AUC) of Leptin will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Adiponectin
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure changes in Adiponectin levels. The area under the plasma concentration versus time curve (AUC) of Adiponectin will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Gastric inhibitory polypeptide (GIP)
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure changes in GIP levels. The area under the plasma concentration versus time curve (AUC) of GIP will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
Change in Insulin
Time Frame: At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.
The researchers will draw blood samples on day 2, at different time points during the trial to measure the change in Insulin levels. The area under the plasma concentration versus time curve (AUC) of Insulin will be calculated using the trapezoidal rule.
At 0 (fast baseline), 0.5, 1, 2, and 3 hours after standardised breakfast.

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
Energy Intake
Time Frame: At 24 hours
To determine the amount of each food item consumed, the researchers will measure the difference in weight between before and after the meal. The researchers will use manufacturer details to determine energy consumption.
At 24 hours

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 Glasgow

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
University of Jazan

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: James Dorling, University of Glasgow

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 (Estimated)

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.
May 1, 2026

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.
June 30, 2027

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.
November 30, 2027

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).
March 24, 2026

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.
March 24, 2026

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 30, 2026

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.
April 16, 2026

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.
April 13, 2026

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.
April 1, 2026

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.
  • 200250171

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

The stored data will be anonymous and follow the guidelines of the General Data Protection Regulation enforced in May 2018. Hard copies of participant information forms, including consent forms and dietary intake records, will be kept in locked filing cabinets. Keys to the filing cabinets will only be available to the primary investigator. All databases will be password protected and stored on a university computer with firewalls.

Participants' identifiable data will be stored in a locked cabinet. Digital data will be stored anonymously within the server of the University of Glasgow.

This project's Principal Investigator will be responsible for sharing the research data. Data will be preserved in Enlighten, the official online repository of Glasgow University's research output.

IPD Sharing Time Frame

The data will be available when the study is completed. Data will be preserved for 10 years.

IPD Sharing Access Criteria

Data will be shared via the repository deposit (Enlighten). Only signatories of end-user agreements can access and use shared data.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

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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Dietary Supplements

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