Investigating how fasting affects energy expenditure in the body

Mechanisms of Fasting Induced Reduction in Energy Expenditure - FIRE Trial

Not applicable Interventional ETH Zurich · NCT06134258

This study is testing how different fasting periods affect energy use in the body and how it relates to thyroid hormones in people who respond differently to fasting.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment40 (estimated)
Ages18 Years to 40 Years
SexAll
SponsorETH Zurich Academic / other
Locations1 site (Basel)
Trial IDNCT06134258 on ClinicalTrials.gov

What this trial studies

This research project aims to explore the mechanisms behind the body's adaptation to fasting, specifically how it affects basal metabolic rate. Initially, a preliminary study will measure the metabolic response of participants to a 24-hour fast. Those with varying responses will be invited to a main study where they will undergo either a 24-hour or an 8-hour fasting period, followed by a mixed meal test to assess energy metabolism and the role of thyroid hormones. The study will also involve taking samples of subcutaneous adipose tissue for further analysis.

Who should consider this trial

Good fit: Ideal candidates for this study are healthy adults aged 18 to 40 with a body mass index between 18.0 and 27.0 kg/m².

Not a fit: Patients with chronic medical conditions requiring treatment, such as diabetes or cardiovascular disease, will not benefit from this study.

Why it matters

Potential benefit: If successful, this study could provide insights into metabolic adaptations to fasting, potentially leading to improved dietary recommendations and interventions for weight management.

How similar studies have performed: While fasting has been studied in various contexts, this specific investigation into the metabolic adaptation mechanisms is relatively novel and has not been extensively tested.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age: 18 to 40 years
* Body mass index 18.0 to 27.0 kg/m²
* Exclusion Criteria:
* Chronic conditions necessitating medical treatment (e.g., renal failure, hepatic dysfunction, cardiovascular disease, diabetes mellitus),
* Known or suspected non-compliance, drug or alcohol abuse,
* Inability to follow the procedures of the study
* Participation in another study with investigational drug within the 30 days preceding and during the present study,
* Previous enrolment into the current study,
* Enrolment of the investigator, his/her family members, employees and other dependent persons,
* Hypothyroidism or hyperthyroidism
* Pregnant, breastfeeding and menopausal women

Where this trial is running

Basel

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions FastingThermogenesis
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.