Weight Loss Composition and Metabolic Adaptation During Hypocaloric Dieting

NCT07627256 | Not Yet Recruiting

• 1 other identifier: 0012134-2
• Study Type: interventional
• Target: 150
• Locations: 0 countries
• Sites: N/A

Brief 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. 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.

Conditions

Obesity

Keywords

Weight loss; Metabolic adaptation; Resting metabolic rate; Body composition; Fat-free mass; Energy expenditure; Hypocaloric diet

Outcome Measures

Primary Outcomes (1)

• Change in Resting Metabolic Rate

  Change in resting metabolic rate (RMR) measured by indirect calorimetry between baseline and post-intervention assessment.

  Baseline to end of dietary intervention (up to 12 months)

Secondary Outcomes (6)

• Change in Fat Mass

  Baseline to end of dietary intervention (up to 12 months)

• Change in Fat-Free Mass

  Baseline to end of dietary intervention (up to 12 months)

• Change in Body Weight

  Baseline to end of dietary intervention (up to 12 months)

• Change in Abdominal Circumference

  Baseline to end of dietary intervention (up to 12 months)

• Intervention Duration

  Baseline to end of intervention (up to 12 months)

Study Arms (1)

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.

Behavioral: Hypocaloric Diet

Interventions

Hypocaloric Diet BEHAVIORAL

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.

Hypocaloric Dietary Intervention

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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.

You may not qualify if:

• 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.

Sponsors & Collaborators

• Tel Aviv University: lead

MeSH Terms

Conditions

Obesity; Weight Loss

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Body Weight Changes

Study Officials

• Yftach Gepner, PhD

  Tel Aviv University

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Yftach Prof. Gepner, PhD

CONTACT

+972 50-682-8501; gepner@tauex.tau.ac.il

Lien Bruck

CONTACT

+972 587487431; lienbruck@tauex.tau.ac.il

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: TREATMENT
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator - Professor

Model Details: 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.

Study Record Dates

• First Submitted: May 31, 2026
• First Posted: June 4, 2026
• Study Start: June 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027
• Last Updated: June 4, 2026

Record last verified: 2026-05

Data Sharing

• IPD Sharing: Will not share