ObesityNCT07627256
Weight Loss Composition and Metabolic Adaptation During Hypocaloric Dieting
A study testing Hypocaloric Diet in people with Obesity, run by Tel Aviv University.
Trial summary
Weight loss induced by hypocaloric dietary interventions is commonly accompanied by reductions in resting metabolic rate (RMR), a phenomenon often described as metabolic adaptation. Read more about this study
- Who is it for?
- Ages 18 years and olderHealthy volunteers can take part
- Conditions the study is for
- Obesity
- What is being tested?
- Hypocaloric Diet
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 150 participants
- Where
- No sites listed yet
- Study dates
- Dec 2026to Dec 2027
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Adults aged 18 years and older.
- Individuals living with overweight or obesity.
- Willingness and ability to comply with dietary recommendations and study procedures.
- Provision of written informed consent.
Who cannot join
- Diagnosed metabolic or endocrine disorders known to affect energy expenditure.
- Use of medications known to substantially affect metabolism or body composition.
- Pregnancy or breastfeeding.
- Any medical condition that, in the opinion of the investigators, precludes safe participation.
Trial locations and contacts
No sites are listed yet. Contact the study team or a site near you to ask about taking part.
About this study
Official title: The Relationship Between Weight Loss Composition, Body Composition Changes, and Metabolic Adaptation During a Hypocaloric Dietary Intervention
Weight loss induced by hypocaloric dietary interventions is commonly accompanied by reductions in resting metabolic rate (RMR), a phenomenon often described as metabolic adaptation. The magnitude of this decline varies substantially between individuals and may depend not only on the amount of weight lost but also on the composition of weight loss, particularly the relative contributions of fat mass and fat-free mass.
This prospective interventional study will investigate whether changes in body composition during a hypocaloric dietary intervention are associated with changes in RMR and metabolic adaptation. Approximately 150 adults with overweight or obesity will participate in a structured dietary program designed to induce moderate energy restriction. Body composition and resting metabolic rate will be assessed before and after the intervention to evaluate associations between fat mass loss, fat-free mass loss, and metabolic responses to weight reduction.
Read the detailed description
Weight loss achieved through caloric restriction is consistently associated with reductions in resting metabolic rate (RMR). In many individuals, the decrease in energy expenditure exceeds what would be predicted from the loss of body mass or body composition alone, a phenomenon commonly described as metabolic adaptation or adaptive thermogenesis. This response has been proposed as one potential contributor to the difficulty many individuals experience in maintaining weight loss over time.
Fat-free mass is the primary determinant of resting energy expenditure because it includes metabolically active tissues such as skeletal muscle and organs. Consequently, the relative proportion of fat mass and fat-free mass lost during weight reduction may influence the magnitude of RMR decline. Dietary strategies that promote preservation of fat-free mass, such as adequate protein intake and engagement in physical activity, may attenuate metabolic slowing during weight loss. However, substantial inter-individual variability in metabolic responses to weight loss has been reported, and the role of weight-loss composition in shaping these responses remains incompletely understood.
The present study aims to examine the relationship between changes in body composition and changes in resting metabolic rate during a structured hypocaloric dietary intervention in adults with overweight or obesity. Participants will follow individualized dietary plans designed to produce a moderate energy deficit. Body composition will be assessed using dual-energy X-ray absorptiometry (DXA), and resting metabolic rate will be measured using indirect calorimetry at baseline and following completion of the intervention. Anthropometric measures and physical activity patterns will also be recorded.
By evaluating the relative contributions of fat mass loss and fat-free mass loss to changes in energy expenditure, this study aims to improve understanding of the physiological responses to weight reduction. The findings may help inform weight-loss strategies designed to minimize unfavorable metabolic adaptations and support more sustainable long-term weight management.
- Conditions
- Obesity
- Being tested
- Hypocaloric Diet
- Keywords
- Weight loss, Metabolic adaptation, Resting metabolic rate, Body composition, Fat-free mass, Energy expenditure, Hypocaloric diet
- Medical subject headings
- Obesity, Weight Loss
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Hypocaloric DietBehavioural
Participants will follow individualized dietary plans designed to produce an energy deficit of approximately 500-600 kcal/day relative to measured resting metabolic rate. Protein intake will be prescribed at approximately 1.5 g/kg body weight per day to support preservation of fat-free mass. Dietary plans will be adjusted as needed during the intervention period, and participants will attend regular follow-up visits to monitor progress and adherence.
| Study group | Role | What they receive |
|---|---|---|
| Hypocaloric Dietary Intervention | Experimental | Participants will follow individualized hypocaloric dietary plans designed to produce a moderate daily energy deficit based on measured resting metabolic rate. The intervention focuses on dietary energy restriction while supporting preservation of fat-free mass through adequate protein intake. Body composition and resting metabolic rate will be assessed before and after the intervention to evaluate metabolic responses to weight loss. Receives: Behavioral: Hypocaloric Diet |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Resting Metabolic Rate
Change in resting metabolic rate (RMR) measured by indirect calorimetry between baseline and post-intervention assessment.
Measured: Baseline to end of dietary intervention (up to 12 months)
Secondary outcomes (6)
Change in Fat Mass
Change in total body fat mass measured using dual-energy X-ray absorptiometry (DXA).
Measured: Baseline to end of dietary intervention (up to 12 months)
Change in Fat-Free Mass
Change in total body fat-free mass measured using dual-energy X-ray absorptiometry (DXA).
Measured: Baseline to end of dietary intervention (up to 12 months)
Change in Body Weight
Change in body weight measured using a calibrated digital scale.
Measured: Baseline to end of dietary intervention (up to 12 months)
Change in Abdominal Circumference
Change in abdominal circumference measured using a standardized anthropometric tape at the midpoint between the lowest rib and iliac crest.
Measured: Baseline to end of dietary intervention (up to 12 months)
Intervention Duration
Total duration of participation in the hypocaloric dietary intervention, recorded in weeks from baseline to intervention completion.
Measured: Baseline to end of intervention (up to 12 months)
Physical Activity Modality
Self-reported type of physical activity performed during the intervention, categorized as aerobic, resistance, combined, or none.
Measured: Baseline to end of dietary intervention (up to 12 months)
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted4 Jun 2026
- Study startDec 2026 (estimated)
- Primary completionDec 2027 (estimated)
- Study completionDec 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for ObesityStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Model description
- Participants will follow individualized hypocaloric dietary plans designed to induce a moderate energy deficit based on measured resting metabolic rate. The study evaluates within-participant changes in body composition and resting metabolic rate during the intervention. All participants receive the same dietary approach, and changes from baseline to post-intervention are assessed.
- Masking
- None (open label)
- Enrolment
- 150 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Tel Aviv University
- Sponsor type
- University, hospital or other
- Responsible party
- Principal investigator, Gepner Yftach, Tel Aviv University
- Investigators
- Yftach Gepner, PhD, Principal investigator, Tel Aviv University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07627256
- Sponsor's protocol ID
- 0012134-2
- Status last verified
- Oct 2026
- First submitted
- 31 May 2026
- Last updated
- 8 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Study at a glance
From the registry record, last updated by the sponsor on 8 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Relationship Between Weight Loss Composition, Body Composition Changes, and Metabolic Adaptation During a Hypocaloric Dietary Intervention
- ClinicalTrials.gov ID
- NCT07627256
- Acronym / sponsor ID
- 0012134-2
- Conditions
- Obesity
- Keywords
- Weight loss, Metabolic adaptation, Resting metabolic rate, Body composition, Fat-free mass, Energy expenditure, Hypocaloric diet
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 150 participants (estimated)
- Lead sponsor
- Tel Aviv UniversityUniversity, hospital or other
- Study start
- Dec 2026 (estimated)
- Primary completion
- Dec 2027 (estimated)
- Study completion
- Dec 2027 (estimated)
- First posted
- 4 Jun 2026 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Weight loss induced by hypocaloric dietary interventions is commonly accompanied by reductions in resting metabolic rate (RMR), a phenomenon often described as metabolic adaptation. The magnitude of this decline varies substantially between individuals and may depend not only on the amount of weight lost but also on the composition of weight loss, particularly the relative contributions of fat mass and fat-free mass.
This prospective interventional study will investigate whether changes in body composition during a hypocaloric dietary intervention are associated with changes in RMR and metabolic adaptation. Approximately 150 adults with overweight or obesity will participate in a structured dietary program designed to induce moderate energy restriction. Body composition and resting metabolic rate will be assessed before and after the intervention to evaluate associations between fat mass loss, fat-free mass loss, and metabolic responses to weight reduction.
Detailed description
Weight loss achieved through caloric restriction is consistently associated with reductions in resting metabolic rate (RMR). In many individuals, the decrease in energy expenditure exceeds what would be predicted from the loss of body mass or body composition alone, a phenomenon commonly described as metabolic adaptation or adaptive thermogenesis. This response has been proposed as one potential contributor to the difficulty many individuals experience in maintaining weight loss over time.
Fat-free mass is the primary determinant of resting energy expenditure because it includes metabolically active tissues such as skeletal muscle and organs. Consequently, the relative proportion of fat mass and fat-free mass lost during weight reduction may influence the magnitude of RMR decline. Dietary strategies that promote preservation of fat-free mass, such as adequate protein intake and engagement in physical activity, may attenuate metabolic slowing during weight loss. However, substantial inter-individual variability in metabolic responses to weight loss has been reported, and the role of weight-loss composition in shaping these responses remains incompletely understood.
The present study aims to examine the relationship between changes in body composition and changes in resting metabolic rate during a structured hypocaloric dietary intervention in adults with overweight or obesity. Participants will follow individualized dietary plans designed to produce a moderate energy deficit. Body composition will be assessed using dual-energy X-ray absorptiometry (DXA), and resting metabolic rate will be measured using indirect calorimetry at baseline and following completion of the intervention. Anthropometric measures and physical activity patterns will also be recorded.
By evaluating the relative contributions of fat mass loss and fat-free mass loss to changes in energy expenditure, this study aims to improve understanding of the physiological responses to weight reduction. The findings may help inform weight-loss strategies designed to minimize unfavorable metabolic adaptations and support more sustainable long-term weight management.
Study design
- Primary purpose
- Treatment
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
- Model description
- Participants will follow individualized hypocaloric dietary plans designed to induce a moderate energy deficit based on measured resting metabolic rate. The study evaluates within-participant changes in body composition and resting metabolic rate during the intervention. All participants receive the same dietary approach, and changes from baseline to post-intervention are assessed.
| Arm | Type | Receives |
|---|---|---|
| Hypocaloric Dietary Intervention | Experimental | Behavioral: Hypocaloric DietParticipants will follow individualized hypocaloric dietary plans designed to produce a moderate daily energy deficit based on measured resting metabolic rate. The intervention focuses on dietary energy restriction while supporting preservation of fat-free mass through adequate protein intake. Body composition and resting metabolic rate will be assessed before and after the intervention to evaluate metabolic responses to weight loss. |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- Adults aged 18 years and older.
- Individuals living with overweight or obesity.
- Willingness and ability to comply with dietary recommendations and study procedures.
- Provision of written informed consent.
Key exclusion criteria (4 listed)
- Diagnosed metabolic or endocrine disorders known to affect energy expenditure.
- Use of medications known to substantially affect metabolism or body composition.
- Pregnancy or breastfeeding.
- Any medical condition that, in the opinion of the investigators, precludes safe participation.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Hypocaloric DietParticipants will follow individualized dietary plans designed to produce an energy deficit of approximately 500-600 kcal/day relative to measured resting metabolic rate. Protein intake will be prescribed at approximately 1.5 g/kg body weight per day to support preservation of fat-free mass. Dietary plans will be adjusted as needed during the intervention period, and participants will attend regular follow-up visits to monitor progress and adherence. | Behavioural | Hypocaloric Dietary Intervention |
Primary outcome
Change in Resting Metabolic Rate
Time frame: Baseline to end of dietary intervention (up to 12 months)
Change in resting metabolic rate (RMR) measured by indirect calorimetry between baseline and post-intervention assessment.
6 secondary outcomes
Change in Fat Mass
Time frame: Baseline to end of dietary intervention (up to 12 months)
Change in Fat-Free Mass
Time frame: Baseline to end of dietary intervention (up to 12 months)
Change in Body Weight
Time frame: Baseline to end of dietary intervention (up to 12 months)
Change in Abdominal Circumference
Time frame: Baseline to end of dietary intervention (up to 12 months)
Intervention Duration
Time frame: Baseline to end of intervention (up to 12 months)
Physical Activity Modality
Time frame: Baseline to end of dietary intervention (up to 12 months)
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Oct 2026.
- Individual participant dataSharing planned: No
Related trials for Obesity
Active, not recruitingPhase 2
Effects of Brain Stimulation on Food Intake and Behavioral Weight Loss Treatment
Electric Stimulation Therapy, Obesity
Not yet recruiting
High-Flow Nasal Oxygen-Assisted Deep Extubation Versus Awake Extubation in Morbidly Obese Patients
Deep Tracheal Extubation
Active, not recruiting
Adipocyte-Derived Extracellular Vesicles, Weight Loss, and Endothelial Function
Obesity, Weight Loss
Not yet recruitingPhase 2
Trial of the Combination of Alpha-Lipoic Acid and Mirabegron in Women and in Men With Obesity
Insulin Resistance, Obesity
Not yet recruitingObservational study
A Natural History of Genetic and Environmental Predictors of Pubertal Timing Among Youth With Obesity
Obesity
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
Yftach Gepner, PhD principal investigator
Tel Aviv University
Questions about this trial
What is this clinical trial studying?
A study testing Hypocaloric Diet in people with Obesity, run by Tel Aviv University.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 4 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 8 Oct 2026. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Yftach Prof. Gepner, PhD (+972 50-682-8501, gepner@tauex.tau.ac.il), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Resting Metabolic Rate (time frame: Baseline to end of dietary intervention (up to 12 months)). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Oct 2026.