Within-Individual Variability of Resting Metabolic Rate Over 12 Weeks

Within-Individual Variability of Resting Metabolic Rate Assessed Repeatedly Over 12 Weeks Using Whole-Room Calorimetry

This prospective observational study aims to characterize within-individual variability in resting metabolic rate (RMR) over a 12-week period using high-frequency repeated measurements under standardized conditions. Participants will undergo RMR assessments three times per week using whole-room indirect calorimetry.

The study will quantify the magnitude of physiological variability in RMR, distinguish true biological variation from measurement error, and estimate the minimal detectable change required to identify meaningful metabolic adaptations.

Study Overview

• Status: Not yet recruiting
• Conditions: Resting Metabolic Rate; Energy Metabolism
• Intervention / Treatment: Other: Repeated Measurement of Resting Metabolic Rate

Detailed Description

Resting metabolic rate (RMR) is a major component of total daily energy expenditure and is widely used in metabolic research. However, most studies rely on single or infrequent measurements, assuming RMR is stable within individuals.

Emerging evidence suggests that RMR exhibits measurable within-individual variability, but the temporal structure and magnitude of this variability remain poorly characterized.

This study will implement a high-frequency repeated-measures design, with RMR measured three times per week over 12 weeks using whole-room indirect calorimetry under standardized conditions. This approach will allow detailed characterization of short-term variability and provide estimates for within-subject variability, measurement error, and minimal detectable change.

The findings will inform interpretation of longitudinal metabolic studies and improve study design in future research.

• Study Type: Observational
• Enrollment (Estimated): 30

Contacts and Locations

• Study Contact: Name: Yftach Prof. Gepner; Phone Number: +972 50-682-8501; Email: gepner@tauex.tau.ac.il
• Study Contact Backup: Name: Lien Bruck; Phone Number: +972 587487431

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Healthy adult men and women from the community, aged 18-65 years, who are clinically healthy and able to participate in repeated metabolic measurements under standardized laboratory conditions.

Description

Inclusion Criteria:

• Adults aged 18-65 years
• Clinically healthy individuals
• Stable body weight (±2 kg) over the past 3 months
• Ability and willingness to attend morning measurements three times per week for 12 weeks
• Ability to provide informed consent

Exclusion Criteria:

• Known uncontrolled endocrine or metabolic disease
• Use of medications known to significantly affect resting metabolic rate (e.g., systemic corticosteroids, unstable thyroid hormone therapy)
• Acute illness within 14 days prior to enrollment
• Pregnancy or lactation
• Any medical condition that, in the opinion of the investigators, may interfere with safe participation

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort	Intervention / Treatment
Healthy Adults; Healthy adult participants undergoing repeated measurements of resting metabolic rate (RMR) three times per week over a 12-week period under standardized conditions. No intervention is applied.	Other: Repeated Measurement of Resting Metabolic Rate; Repeated assessment of resting metabolic rate under standardized conditions; no intervention is administered.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-Individual Variability in Resting Metabolic Rate (RMR)	Within-individual variability in resting metabolic rate (RMR) assessed using repeated measurements under standardized conditions. Variability will be quantified using mean, standard deviation (SD), and coefficient of variation (CV%) across repeated measurements.	12 weeks

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Minimal Detectable Change (MDC) in RMR	The minimal detectable change in resting metabolic rate required to distinguish true physiological change from measurement variability.	12 weeks
Between-Individual Variability in RMR	Assessment of variability in resting metabolic rate between participants based on repeated measurements.	12 weeks
Temporal Trends in RMR	Assessment of systematic changes in resting metabolic rate over time using repeated measurements across the study period.	12 weeks

Collaborators and Investigators

• Sponsor: Tel Aviv University
• Investigators: Principal Investigator: Yftach Prof. Gepner, Tel Aviv University

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 1, 2027
• Study Completion (Estimated): December 1, 2027

Study Registration Dates

• First Submitted: June 1, 2026
• First Submitted That Met QC Criteria: June 1, 2026
• First Posted (Actual): June 5, 2026

Study Record Updates

• Last Update Posted (Actual): June 5, 2026
• Last Update Submitted That Met QC Criteria: June 1, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Energy Expenditure; Metabolism; Variability; Resting Metabolic Rate; Indirect Calorimetry
• Other Study ID Numbers: 0012137-2

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No