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NCT Number: NCT07036562

Time-restricted Eating and High-intensity Interval Training for Metabolic Health in Adults With Overweight/Obesity

This study will investigate the effects of 12 months periodised time-restricted eating combined with high-intensity interval training compared with a control group on fat mass in adults with overweight/obesity. Participants in the intervention group will complete the intervention remotely and will receive follow-up by telephone. Before randomisation, after 6 months and after 12 months, the investigators will measure the participants' body composition, physical fitness, fasting blood glucose and insulin, blood lipids, and blood pressure. Physical activity, diet, sleep quality, appetite, and adherence to the intervention will also be measured. Secondary sub-analyses of sex differences in the responses to the intervention will be performed.

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Key information

Conditions

Overweight and Obesity Behavior Body Weight Fasting Feeding Behavior Intermittent Fasting Motor Activity Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms

Age range

18 year–50 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Department of circulation and medical imaging, NTNU

Trondheim, 7491, Norway

Location status: Recruiting

Location contact

Beathe Sitter, PhD

CONTACT

[email protected]

+47 73412318

Kamilla La Haganes, PhD

SUB_INVESTIGATOR

Trine Moholdt, PhD

PRINCIPAL_INVESTIGATOR

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Body mass index ≥ 27 kg/m²
  • Able to walk or ride a bike > 60 min

Exclusion criteria

  • On-going pregnancy
  • Lactation within 24 weeks of study commencement
  • High-intensity exercise ≥ 1/week
  • Habitual eating window ≤12 hours/day
  • Taking hypertension, glucose-, or lipid-lowering drugs
  • Body mass variation ≥ 4 kg three months prior to study commencement
  • Known diabetes mellitus (type 1 or 2) or cardiovascular disease
  • Working night shifts

Treatment and study plan

Time-restricted eating and high-intensity interval training

Behavioral

1-month intense periods of maximal daily eating window of 10 hours and high-intensity interval training (three weekly, unsupervised, aerobic exercise sessions performed at > 90 % heart rate maximum), separated by 3-month maintenance periods of time-restricted eating on 5 days per week and minimum 1 HIIT session per week. Each exercise session will last for 33-38 minutes. Participants will receive digital follow-up once weekly during intense periods, and once monthly during maintenance periods. The intervention period will be 12 months in total.

Primary outcomes

  1. Total fat mass

    Time frame: From baseline to after 12 months

    Change in total fat mass measured with bioelectrical impedance analysis

Secondary outcomes

  1. Blood glucose

    Time frame: From baseline to after 6 months and after 12 months

    Fasting concentration of plasma glucose

  2. Total fat mass

    Time frame: From baseline to after 6 months

    Change in total fat mass measured with bioelectrical impedance analysis

  3. Insulin

    Time frame: From baseline to after 6 months and after 12 months

    Fasting concentration of plasma insulin C-peptide

  4. Average glucose levels

    Time frame: From baseline to after 6 months and after 12 months

    Glycated haemoglobin (HbA1c)

  5. Blood cholesterol

    Time frame: From baseline to after 6 months and after 12 months

    Total fasting cholesterol in blood

  6. LDL-cholesterol

    Time frame: From baseline to after 6 months and after 12 months

    Fasting low-density lipoprotein-cholesterol in blood

  7. HDL-cholesterol

    Time frame: From baseline to after 6 months and after 12 months

    Fasting high-density lipoprotein-cholesterol in blood

  8. Triglycerides

    Time frame: From baseline to after 6 months and after 12 months

    Fasting triglycerides in blood

  9. Cardiorespiratory fitness

    Time frame: From baseline to after 6 months and after 12 months

    Peak oxygen uptake at a maximum effort test, measured in mL/min/kg and L/min

  10. Insulin sensitivity

    Time frame: From baseline to after 6 months and after 12 months

    Homeostatic model assessment for insulin resistance (HOMA-IR): 1.5 + fasting plasma glucose (mmol/L) x fasting plasma insulin C-peptide (pmol/L)/2800

  11. Body mass

    Time frame: From baseline to after 6 months and after 12 months

    In kg, estimated with bioelectrical impedance analysis

  12. Fat-free mass

    Time frame: From baseline to after 6 months and after 12 months

    In kg, estimated with bioelectrical impedance analysis

  13. Visceral fat area

    Time frame: From baseline to after 6 months and after 12 months

    In cm2, estimated with bioelectrical impedance analysis

  14. Systolic blood pressure

    Time frame: From baseline to after 6 months and after 12 months

    Average of three measurements during rest in seated position, in mmHg

  15. Diastolic blood pressure

    Time frame: From baseline to after 6 months and after 12 months

    Average of three measurements during rest in seated position, in mmHg

  16. Resting heart rate

    Time frame: From baseline to after 6 months and after 12 months

    Average of three measurements during rest in sitting position, in beats/min

  17. Physical activity levels

    Time frame: From baseline to after 6 months and after 12 months

    International Physical Activity Questionnaire

  18. Diet intake

    Time frame: During baseline week, after 4, 13, 30, and 50 weeks.

    3-day diet diaries (two weekdays and one weekend day) with online diet diary.

  19. Sleep quality

    Time frame: From baseline to after 6 months and after 12 months

    The Pittsburgh Sleep Quality Index questionnaire

Other outcomes

  1. Adherence to high-intensity interval training

    Time frame: 12 months

    Number of completed exercise sessions out of those prescribed, in percentage

  2. Compliance to high-intensity interval training

    Time frame: 12 months

    Exercise intensity measured with pulse sensor. Heart rate percentage of individual heart rate maximum.

  3. Adherence to time-restricted eating

    Time frame: During baseline week, after 4, 13, 30, and 50 weeks.

    Average number of days per week a daily eating window of 10 hours or less was achieved

  4. Compliance to time-restricted eating

    Time frame: During baseline week, after 4, 13, 30, and 50 weeks.

    Average daily eating window, self-reported in hours/day

  5. Perception of intervention and digital follow-up

    Time frame: After 12 months

    Qualitative interviews with selected participants to explore barriers and motivators

  6. Sex differences

    Time frame: From baseline to after 6 months and after 12 months

    Sub-analyses of sex differences in the effectiveness of the intervention

Study contacts

Contact information is provided by the study sponsor or research team.

Kamilla La Haganes, PhD

CONTACT

[email protected]

+4747316765

Trine Moholdt, PhD

CONTACT

[email protected]

+4797098594

Sponsors and collaborators

Lead sponsor

Norwegian University of Science and Technology

Other

Registry information

Official study title

Time-restricted Eating and High-intensity Interval Training for Long-term Improvement in Metabolic Health

Acronym: TREHIIT-3

Important dates

Study start
2025
Primary completion
2027
Study completion
2027
First posted
Jun 25, 2025
Registry last updated
Dec 12, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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