Time Restricted Eating and Meal Frequency for Appetite Control (TRE)

September 2, 2026 updated by: University of Aberdeen

Time-restricted Eating (TRE) and Meal Frequency to Influence Appetite Control in Adults With Overweight or Obesity: a Randomized Crossover Trial

Obesity is one of the largest worldwide health problems. There are increasing rates of overweight and obesity, and in recent years, worldwide the percentage of overweight and obesity among adults now exceeds 1.9 billion and 650 million, respectively. Overweight and obesity are associated with an increase risk of type 2 diabetes (T2D), coronary heart disease, hypertension and other non-communicable diseases. There are multiple nutritional causes for obesity, including both the type and amount of food consumed. Other non-nutritional factors can be just as important to influence body mass, such as the number of meals eaten, which is termed meal frequency. The changing food environment influences calorie consumption, such as increased food variety, increased availability and food processing, a nocturnal lifestyle that disrupts the circadian clock, meal timing and frequency, irregular meal patterns, and prolonged duration of eating during the day. This results in increased food and beverage consumption throughout the day. Meal frequency is commonly defined as, 'the number of foods or drinks a person consumes in one day. Meals and snacks are less clearly defined. Meal is defined as any food providing≥ 50 kcal and separated by more than one hour. In most cultures, the name meal is given to the three eating episodes in a day: breakfast, lunch, and dinner; or breakfast, brunch, lunch, supper, and dinner. In this study, the investigators will use the definition of "breakfast, brunch, lunch, supper, and dinner", but it will be on restricted time: 10 hours eating and 14 hours fasting (from 7:00 to 17:00) and one type of diet (high protein diet). Other researchers have defined meals by the time of the day, such as early and late breakfast, lunch and dinner intake. These definitions differ according to culture. Other researchers have defined meals based on timing, such as (6:00 am -10:00 am), (12:00 pm - 3:00 pm), and (6:00 pm - 9:00 pm). Some studies have highlighted that there are factors that affect the number of meals which a person consumes. Eating a high amount of energy during breakfast helps to feel full for a longer period. Time of eating and duration of eating or not eating. The type of macronutrient intake; for example, high protein (HP) intake reduces ad libitum energy intake. The number of meals eaten per day; some studies have confirmed that consuming small frequent meals is better for healthy weight and appetite control in the general population, compared to consuming one huge meal a day. This can assist control of appetite and plasma glucose concentrations. On the other hand, recent research has indicated that consuming (≥6 meals/day) increases disease risk significantly more than consuming (1-2 meals/day). Some researchers believe that there is no relationship between meal frequency and body weight.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

Number of Participants:

10 adults (males and females) who have expressed an interest in taking part and meet the inclusion criteria. Should there be any withdrawals, the investigators will continue to replace participants until 10 have completed the trial.

The primary objective of this study was to explore the efficacy and physiological responses to a controlled time-restricted eating regime and dietary interventions (2 or 5 meals per day) on the participant's appetite response, measured with visual analogue scales (VAS). VAS is completed on test days (recorded at time points 0, 30, 60, 90, 120, 150 and 180 minutes) and on all other study days (recorded hourly during waking hours). The secondary objective is to compare the influence of dietary interventions (2 or 5 meals per day) on the following: plasma fasting blood glucose and 3 hours post-prandially after a standardized test meal. Analysed by KONE for timepoints 0 and 180 mins. Plasma fasting insulin and 3 hours post-prandially after a standardized test meal. Analysed by ELISA for timepoints 0 and 180 mins. Continuous glucose monitoring System (CGMS) on all study days to assess free-living glycaemic control in response to diet. All components of energy expenditure and substrate utilization are monitored by ventilated hood (indirect calorimetry) as resting metabolic rate (RMR, 30 minutes before eating breakfast); thermic effect of food (TEF postprandial 3 hours, measured 10 minutes every 30 minutes by the ventilated hood). Moreover, to assess changes in physical activity, with accelerometry on all study days and the Baecke Physical Activity Questionnaire (BPAQ) completed on each test day. To assess if meal frequency influences sleep, a sleep diary will be completed on all study days and the Epworth Sleepiness questionnaire (ESQ) completed on each test day. Finally, to assess if meal frequency influences body mass and body composition (fasted body weight measured on all food collection and test days), and fasted waist and hip circumferences and fat mass by bio-impedance analysis (BIA) measured on all test days.

A randomized crossover trial (RCT). Each participant will complete a 21 day study design as follows:

  • 7 days food diary (recording at home, habitual diet) [Days -6 to 0].
  • 2 days maintenance diet 1 (MT1) [Days 1-2].
  • Test Day on Day 3.
  • 4 days intervention weight loss diet (2MPD, 2 meals/day or 5MPD, 5 meals/day) [Days 3-6].
  • Test Day on Day 7.
  • 8 days washout period, no meals provided [Days 7-14].
  • 2 days maintenance diet 2 (MT2) [Days 15-16].
  • Test Day on Day 17.
  • 4 days intervention weight loss diet (5MPD, 5 meals/day or 2MPD, 2 meals/day) [Days 17-20].
  • Test Day on Day 21.

Study Diets:

During the screening visit, RMR was measured for each participant, and based on the results, each participant received a different meal portion. After receiving the RMR results for each participant, the kitchen staff at the Human Intervention Studies Unit (HISU) were emailed the participant number, RMR results, and the randomised diet they would start (2MPD or 5MPD), allowing the dietitian to assign the closest diet on the diet scales (1250, 1500, 1750, 2000, 2250 kcal). For example, if the RMR result for a volunteer were 1800 kcal, it would be put in the closest diet, 1750 kcal.

All food will be prepared at the Human Intervention Studies Unit (HISU), Rowett Institute.

This study will include two types of diet:

  • A maintenance diet (MT, 15:30:55% of energy from protein, fat and carbohydrate respectively). On days 1-2 (MT1) and 15-16 (MT2) this diet will be fed to meet measured energy requirements (1.5 x Resting Metabolic Rate, RMR).
  • A high protein (HP) intervention weight loss diet (WL, 30:35:35% of energy from protein, fat and carbohydrate respectively). On days 3-6 (WL1) and 17-20 (WL2) this will be fed to 100% resting metabolic rate. The food intake during the intervention periods will be randomized for two patterns fed between 07:00 to 17:00; five small meals per day (5MPD) and two large meals per day (2MPD). The protein in the diets will come from different sources like meat, poultry, fish, soy, and beans. In addition, all meals on the diets will contain equal proportions of protein so that the daily protein is not all consumed in one meal.

Study Measurements:

In total there will be nine study visits to the Human Intervention Studies Unit (HISU), Rowett Institute: one screening visit, which last approximately 2 hours, 4 visits for Test Days representing pre and post dietary phases (day 3rd, 7th, 17th, and 21st), which last approximately 4-5 hours, and 6 visits to collect food (day 1st, 3rd, 6th, 15th, 17th, and 20th), two of them are at the same day of Test Day, which last approximately 30 mins, except 2 visits will be 4-5 hours because it is the day of Test Days too. All visits details are described in the protocol. Researcher(s) carrying out the procedure: The study will be co-ordinated by a Research Team, consisting of Professor Alexandra Johnstone (PI), Prof Justin Rochford (CI), Ms Nouf Alkhattabi (PhD student), Claire Fyfe (Research Technician), David Bremner (Research Assistant), Claire Kidd (Research Assistant), Christina Petkov (Honorary Research Nurse).

Screening Visit:

The participant should already have a copy of the PIS in advance of the consent and screening visit should already have a good understanding of the study and have sufficient time to read it before this visit. After discussion, the consent should always be obtained before the health status and eligibility. n=10 to complete.

All measurements will be conducted after a fast from 10:00 pm the night before. Breakfast will be provided at the end of the screening visit.

Screening will continue until study completion and involves.

  • Completing written, informed consent paperwork (PIS and consent form).
  • A self-report general health screening questionnaire.
  • RMR measurement for calculation of energy requirements (ventilated hood).
  • Height and weight measurements to calculate body mass index (BMI).

The participants will then be given a 7-day weighed intake food diary and scales to take away with them to complete to establish their regular eating habits before the start of diet provision.

Test Day Visits (on Days 3, 7, 17 and 21):

All measurements will be conducted after a fast from 10pm the night before. On days 3 and 17 meals will be provided as breakfast, lunch, dinner, and snacks according to the intervention diet randomisation (2MPD or 5MPD), while on days 7 and 21 only breakfast will be provided.

  • Overnight fasted anthropometric measures

    • Body weight and body mass index (BMI) calculation.
    • Total body fat (TBF), fat mass (FM) and fat-free mass (FFM) by bio-impedance analysis (BIA).
    • Waist and hip circumferences measured using a tape measure.
    • Resting energy expenditure (RMR) will be measured for 30mins in fasting state by indirect calorimetry.
  • The blood samples will be collected by multiple venepuncture (T0 and T180mins).

  • Venepuncture for fasted blood sampling (one 4ml LiHep tube):

    • T0mins Glucose (1x500μl plasma in KONE cup).
    • T0mins Insulin (1x300μl plasma in 0.5ml Eppendorf).
    • T0mins LiHep Spare (2x300μl plasma in 1.5ml Eppendorf).

The total volume of blood taken will be as follows:

  • In each visit, 8ml will be taken for each participant.

  • The total blood taken for 4 visits will be 32ml for each participant.

    • Measure of fasted participant appetite by Visual Analogue Scales (VAS) at T0mins.
    • Consumption of intervention breakfast meal at T0.
    • After the test meal the thermic effect of food (TEF) will be calculated from indirect calorimetry measurements taken for the last 10 min of every 30 min up to 3 hours (T20, T50, T80, T110, T140 and T170mins).
    • Questionnaires:
  • A validated self-report questionnaire for physical activity Baecke Physical Activity Questionnaire (BPAQ) and the sedentary is categorized as, low, medium, or high.
  • Assessment of how meal frequency influences sleep using the Epworth Sleepiness questionnaire (ESQ).

  • Post-prandial measurement of participant appetite by VAS at T30, T60, T90, T120, T150 and T180mins.

    • Venepuncture for postprandial blood sampling (one 4ml LiHep tube):

  • T180mins Glucose (1x500μl plasma in 0.5ml KONE cup).
  • T180mins Insulin (1x300μl plasma in 0.5ml Eppendorf).

  • T180mins LiHep Spare (2x300μl plasma in 1.5ml Eppendorf).

    • Food diary recorded for the remainder of the day.

Other Measurements:

  • Continuous Glucose Monitoring System (CGMS) throughout the 3week study (two, 2week insertions per participant) using Freestyle Libre devices. Sensors record data for 14 days at a time. Freestyle Libre sensor: water resistant sensor (in up to 1m water for a maximum of 30mins) that continuously measures the glucose concentration in interstitial fluid, and stores 8 hours of data. Can be scanned by any mobile device capable of downloading the FreeStyle LibreLinkUp app. LibreLinkUp is compatible with Android and iOS smartphones which meet the following requirements: Android OS 6.0 (or higher) or iOS 11 (or higher) and an internet connection. Participants without a smartphone capable of using the app will be provided with a budget smartphone. Each sensor has a working life of 2 weeks. Participants will be supplied with the required number of sensors in order to complete the study. The FreeStyle Libre sensor is applied on to the back of the upper arm with a simple, disposable device called an applicator. When the sensor is applied, a thin, flexible and sterile fibre is inserted just under the skin. It is held in place with a small adhesive pad. In a study conducted by Abbott, users agreed that inserting the sensor was no more painful than a typical finger prick test. To obtain a glucose reading from this device, participants must perform a quick, painless 1-second scan of the reader over the sensor. This scan gives the investigators more information than monitoring with blood glucose test strips, without the need for routine finger pricks. Each scan of the reader over the sensor gives a current glucose reading, the last 8-hours of glucose history, and a trend arrow showing if glucose is going up, down, or changing slowly. The reader can scan through clothing.
  • Temporal changes in appetite using VAS questionnaires throughout the 2 intervention phases of the study. Questionnaires completed hourly during waking hours.
  • Composition of all meals consumed during the 3weeks study. Recorded by participants using weighback sheets and the food scales provided at the screening visit.
  • Physical activity levels recorded by Actigraph accelerometers. The actigraph provides data for energy expenditure per day, the intensity of the activity carried out taken when the monitor was worn.
  • Assessment of how meal frequency influences sleep. Hours slept will be calculated from the data recorded by the Actigraph accelerometers and from two, 7day sleep diaries with questions the participants will answer every morning of the intervention phases.

Study Type

Interventional

Enrollment (Actual)

12

Phase

  • 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 Locations

  • United Kingdom
    • Aberdeen City
      • Aberdeen, Aberdeen City, United Kingdom, AB25 2ZD
        • University of Aberdeen, The Rowett Institute, Foresterhill

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

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  • Adults (males and females), age 18-65 years
  • Who are healthy but overweight or obese (BMI 25+ Kg/m2)
  • With no history of kidney disease or bariatric surgery
  • Not following any specific type of medical or religious diet
  • Not taking any drugs that affect the rate of physical activity or metabolic circulating
  • Not pregnant or breastfeeding.
  • With a fluent understanding of the English language

Exclusion Criteria:

  • Anyone with a BMI (in kg/m2) under 25
  • Anyone under 18 years or above 65 years.
  • Anyone taking the statins (current), aspirin or anti-coagulants (current).
  • Anyone with chronic inflammatory disorders such as rheumatoid arthritis or inflammatory bowel disease
  • Anyone with cardiovascular disease
  • Anyone with diabetes
  • Anyone who is are planning to be pregnant, are pregnant or breastfeeding
  • Anyone with food allergy, self-reported food sensitivity or intolerance
  • Anyone with coeliac disease or gluten intolerance
  • Anyone with a gastrointestinal disorder, kidney disease, liver disease or gout
  • Anyone taking medication which may affect appetite or circadian rhythm.
  • Anyone with an eating disorder
  • Anyone suffering from unregulated thyroid disease.
  • Anyone using Beta Blockers which can affect the rate of physical activity.
  • Anyone using some anti-depressants such as mirtazapine can affect the appetite.
  • Anyone following a vegetarian or vegan diet
  • Anyone following a weight loss programme (that may affect lifestyle, physical activity & diet)
  • Anyone with unsuitable veins for blood sampling
  • Anyone who is unable to fluently speak, read and understand English
  • Anyone who is unable to comply with an alcohol-free diet for 3 weeks
  • Anyone consumption of nutrition supplements
  • Anyone has the intention to donate blood within 2 months of the study.
  • Anyone intending to travel away from Aberdeen during the intervention phase.
  • Anyone who is a shift worker.
  • Anyone who smokes including e-cigs or vaping.
  • Anyone recently participated in any other research studies during the last 4 weeks.

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: Health Services Research
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: weight loss diet 1 (2MPD)
Intervention weight loss diet 1 (2MPD, 2 meals/day) for 4 days
Other: MT1
- On days 1-2 (MT1) 15:30:55% of energy from protein, fat and carbohydrate respectively).
Other: MT2
- On days 16-17 (MT2) 15:30:55% of energy from protein, fat and carbohydrate respectively).
Experimental: weight loss diet2 (5MPD)
Intervention weight loss diet 2 (5MPD, 5 meals/day) for 4 days
Other: MT1
- On days 1-2 (MT1) 15:30:55% of energy from protein, fat and carbohydrate respectively).
Other: MT2
- On days 16-17 (MT2) 15:30:55% of energy from protein, fat and carbohydrate respectively).

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
The participant's appetite response on the test day (day 3rd, 7th, 17th, and 21st)
Time Frame: On test days recorded at timepoints 0, 30, 60, 90, 120, 150 and 180 minutes. On all study days recorded hourly during waking hours. The straight line is 100 mm long, left side indicates low symptoms.
Measured with visual analogue scales (VAS).
On test days recorded at timepoints 0, 30, 60, 90, 120, 150 and 180 minutes. On all study days recorded hourly during waking hours. The straight line is 100 mm long, left side indicates low symptoms.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Plasma blood glucose on the test day (day 3rd, 7th, 17th, and 21st)
Time Frame: The blood samples will be collected by multiple venepuncture before breakfast (T0 minutes) and post prandial (T180 minutes).
The plasma fasting blood glucose and 180 minutes post-prandially after a standardized test meal which is analysed by KONE system.
The blood samples will be collected by multiple venepuncture before breakfast (T0 minutes) and post prandial (T180 minutes).
Plasma blood insulin on the test day (day 3rd, 7th, 17th, and 21st)
Time Frame: The blood samples will be collected by multiple venepuncture before breakfast (T0 minutes) and post prandial (T180 minutes).
Plasma fasting blood insulin (T0 minutes) and (T180 minutes) post-prandially after a standardized test meal which analysed by ELISA.
The blood samples will be collected by multiple venepuncture before breakfast (T0 minutes) and post prandial (T180 minutes).
Continuous glucose monitoring System (CGMS)
Time Frame: Day 1-7 and day 15-21 which correspond to weight loss diet periods.

The device measures the glucose levels during day over 7 days when it is worn and will enable us to determine the volunteer body's responses to the meals.

Two CGMS sensors will be fitted during the study:

  • on the 1st day of the study (removed on study day 7).
  • on the 15th day of the study (removed on study day 21).
Day 1-7 and day 15-21 which correspond to weight loss diet periods.
Resting Metabolic Rate (RMR) on test day (day 3rd, 7th, 17th, and 21st)
Time Frame: Resting metabolic rate (RMR, 30 minutes before eating breakfast) on screening visit and Test Day (3, 7, 17, and 21).
All components of energy expenditure and substrate utilization are monitored by ventilated hood (indirect calorimetry).
Resting metabolic rate (RMR, 30 minutes before eating breakfast) on screening visit and Test Day (3, 7, 17, and 21).
Thermic Effect of Food (TEF ) on test day (day 3rd, 7th, 17th, and 21st)
Time Frame: Thermic effect of food (TEF post prandial 180 minutes, measured 10 minutes, every 30 minutes by ventilated hood; at 30, 60, 90, 10, 150, and 180 minutes) on Test Day 3, 7, 17, and 21.
All components of energy expenditure and substrate utilization are monitored by ventilated hood (indirect calorimetry).
Thermic effect of food (TEF post prandial 180 minutes, measured 10 minutes, every 30 minutes by ventilated hood; at 30, 60, 90, 10, 150, and 180 minutes) on Test Day 3, 7, 17, and 21.
Physical activity (Actigraphy)
Time Frame: - accelerometery (Actigraphy) on all study days, measured on days 1-7 and days 15-21).
To assess changes in physical activity with the accelerometery (Actigraphy).
- accelerometery (Actigraphy) on all study days, measured on days 1-7 and days 15-21).
Physical activity (BPAQ)
Time Frame: - the Baecke Physical Activity Questionnaire (BPAQ) completed tow times, on Day 3, 7, 17, and 21.
To assess changes in physical activity with the Baecke Physical Activity Questionnaire (BPAQ).
- the Baecke Physical Activity Questionnaire (BPAQ) completed tow times, on Day 3, 7, 17, and 21.
Sleep (Actigraphy)
Time Frame: Actigraphy worn on all study days (day 1-7 and day 15-21).
To assess if meal frequency influences sleep using Actigraphy monitor.
Actigraphy worn on all study days (day 1-7 and day 15-21).
Sleep
Time Frame: A sleep diary completed on all study days (Day 1-7 and day 15-21).
To assess if meal frequency influences sleep using a sleep diary
A sleep diary completed on all study days (Day 1-7 and day 15-21).
Sleep (ESQ)
Time Frame: The Epworth Sleepiness questionnaire (ESQ) on all test days (Day 3, 7, 17, and 21).
To assess if meal frequency influences sleep using the Epworth Sleepiness questionnaire (ESQ)
The Epworth Sleepiness questionnaire (ESQ) on all test days (Day 3, 7, 17, and 21).
Body Weight
Time Frame: Fasted body weight measured on all food collection (Day 1, 3, 6, 15, 17, and 20) and test days (Day 3, 7, 17, and 21).
Our study for measured the body weight used the OHAUS CD-11 scale to the nearest 0.1 kg.
Fasted body weight measured on all food collection (Day 1, 3, 6, 15, 17, and 20) and test days (Day 3, 7, 17, and 21).
Hight
Time Frame: Hight measured once only at screening visit to calculate BMI.
The investigators used the Stadiometer (Seca 213) to the nearest 0.1 cm for height measurement.
Hight measured once only at screening visit to calculate BMI.
Body Composition
Time Frame: BIA measure on test day (Day 3, 7, 17, and 21).
To measure the fat mass (kg) and fat-free (kg) mass by bio-impedance analysis (BIA)
BIA measure on test day (Day 3, 7, 17, and 21).
Waist and Hip Circumference
Time Frame: On test day (Day 3, 7, 17, and 21).
To assess waist and hip circumferences change measured using a tape measure, recorded in mm.
On test day (Day 3, 7, 17, and 21).

Collaborators and Investigators

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

Sponsor

University of Aberdeen

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

September 12, 2024

Primary Completion (Actual)

April 14, 2025

Study Completion (Actual)

August 31, 2025

Study Registration Dates

First Submitted

May 20, 2026

First Submitted That Met QC Criteria

September 2, 2026

First Posted (Actual)

September 4, 2026

Study Record Updates

Last Update Posted (Actual)

September 4, 2026

Last Update Submitted That Met QC Criteria

September 2, 2026

Last Verified

February 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 2807965
  • 1GF1B20B2 (Other Grant/Funding Number: Saudi Arabian Cultural Bureau in the UK)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

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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