Exercise and Prolonged Fasting to Improve Brown Adipose Tissue Function in Postmenopausal Women (EMPOWER-BAT)

September 17, 2026 updated by: Borja Martínez Tellez, Universidad de Almeria

Exercise and Prolonged Fasting to Improve Interscapular Brown Fat Mitochondrial Function and Enhance Metabolic Flexibility in Postmenopausal Women (EMPOWER-BAT)

Type of Study: Clinical Trial

Goal: The goal of this clinical trial is to investigate mitochondrial function in interscapular brown adipose tissue (iBAT) in postmenopausal women and determine whether aerobic exercise, prolonged fasting, or their combination can improve iBAT mitochondrial function and whole-body metabolic flexibility.

Participant Population/Health Conditions: The study will involve 60 postmenopausal women aged 45-65 years living with overweight or obesity.

Main Questions: The main questions this study aims to answer are:

  • What are the mitochondrial function and cellular characteristics of iBAT in postmenopausal women?
  • Can aerobic exercise or five-day prolonged fasting improve mitochondrial function in iBAT and whole-body metabolic flexibility?
  • Does combining aerobic exercise with prolonged fasting produce greater metabolic adaptations than either intervention alone?
  • Are improvements in metabolic flexibility maintained four weeks after the intervention?

Participants Will:

Be randomized into one of four groups: control, aerobic exercise, prolonged fasting, or combined aerobic exercise plus prolonged fasting.

Follow their assigned intervention for five consecutive days. Undergo metabolic and physiological assessments before and after the intervention and again four weeks later.

Provide dorsocervical adipose tissue biopsies and biological samples to investigate mitochondrial function, adipocyte characteristics, and metabolic adaptations.

Comparison Group: Researchers will compare the effects of aerobic exercise, prolonged fasting, and their combination with a control condition to determine their effects on iBAT mitochondrial function and whole-body metabolic flexibility.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Not yet recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Postmenopause is associated with a substantial increase in cardiometabolic risk, partly driven by the decline in estrogen levels and alterations in cellular energy metabolism. Mitochondrial dysfunction has been documented in skeletal muscle of postmenopausal women and is associated with metabolic inflexibility, reduced fat oxidation, ectopic fat accumulation, and insulin resistance. However, whether mitochondrial dysfunction is also present in adipose tissue of postmenopausal women, and whether it can be reversed through lifestyle interventions, remains largely unknown.

Brown adipose tissue (BAT) is a mitochondria-rich and metabolically active tissue involved in thermogenesis and substrate utilization. Although human BAT has traditionally been studied in the supraclavicular region, emerging evidence from our research group suggests the presence of a metabolically active adipose tissue depot in the dorsocervical region, referred to as interscapular brown adipose tissue (iBAT). Preliminary observations indicate that this depot may have distinct metabolic characteristics. However, iBAT has not yet been characterized in postmenopausal women.

Aerobic exercise is a potent non-pharmacological stimulus for mitochondrial remodeling and improves mitochondrial biogenesis and oxidative capacity. Exercise-derived lactate may also promote adipose tissue browning and mitochondrial remodeling. Prolonged fasting induces profound metabolic adaptations characterized by increased fat mobilization and changes in substrate utilization. Preliminary data from our group suggest that five days of prolonged fasting substantially increase fat oxidation during exercise, providing a rationale for investigating whether fasting and exercise may have complementary effects on mitochondrial function and metabolic flexibility.

Based on this rationale, the main hypothesis of EMPOWER-BAT is that iBAT in postmenopausal women presents mitochondrial dysfunction and that aerobic exercise, five-day prolonged fasting, and their combination can improve mitochondrial function through lactate-related signaling pathways, leading to enhanced whole-body metabolic flexibility. The main objective is to characterize mitochondrial function in iBAT and determine the effects of these interventions on iBAT mitochondrial function and metabolic flexibility.

EMPOWER-BAT is a randomized controlled trial involving 60 postmenopausal women aged 45-65 years with a body mass index ≥25 kg/m². Participants will be randomized (1:1:1:1) into four groups: a control group maintaining its usual lifestyle; an aerobic exercise group performing supervised exercise for 60-90 minutes at 65% of heart rate reserve; a prolonged fasting group following a medically supervised fasting protocol providing approximately 600 kcal/day; or a combined group completing both exercise and fasting. All interventions will last five consecutive days.

Before and after the intervention, iBAT biopsies will be collected from the dorsocervical region to assess mitochondrial function and adipocyte characteristics. Metabolic and physiological assessments will include indirect calorimetry at rest and during exercise, body composition, cardiorespiratory fitness, and blood and urine biomarkers. Continuous glucose and ketone monitoring will also be performed during the intervention. Four weeks later, metabolic and physiological assessments will be repeated to determine whether changes in metabolic flexibility are maintained after participants return to their usual lifestyle.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
60

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.
  • Name: Borja Martínez Téllez, PhD
  • Phone Number: +34 950215334
  • Email: borjammt@ual.es

Study Locations

  • Spain
    • Almería
      • Almería, Almería, Spain, 04131
        • Universidad de Almería

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

45 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

Female

Description

Inclusion Criteria:

  • Women aged 45 to 65 years.
  • Postmenopausal status, defined as ≥ 12 consecutive months without menstruation.
  • Women with amenorrhea shorter than 12 months will be included if their follicle-stimulating hormone levels are >30IU/liter.
  • BMI between ≥25 kg/m2.
  • Sedentary or low-active (not meeting physical activity guidelines).
  • Willing to be randomized to any of the four groups.
  • Able and willing to adhere to all study procedures and show availabity in their schedule.
  • Must be willing to have biological samples stored for future research.

Exclusion Criteria:

  • Diabetes mellitus (determined based on fasting glucose levels defined by ADA criteria).
  • Any other active endocrine disease (thyroid disease, any signs of Cushing's syndrome, adrenal disease and lipid-associated disorders such as familial hypercholesterolemia).
  • Any cardiac disease (i.e., ischemic cardiac disease, arrhythmias, severe heart failure).
  • Use of medication known to influence glucose and/or lipid metabolism or brown fat activity (e.g., beta-blockers, antidepressants, corticosteroids).
  • Current or recent (past 6 months) use of hormone replacement therapy, including systemic estrogen therapy (oral or transdermal), combined estrogen-progestin therapy, tibolone, or selective estrogen receptor modulators.
  • Clinically relevant abnormalities in clinical chemistry or electrocardiogram at screening (to be judged by the study physician).
  • A first-degree family member with sudden cardiac death.
  • Any chronic renal or hepatic disease.
  • Abuse of alcohol or other substances.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
No Intervention: Control

n=15; maintaining their usual lifestyle without changes to diet or physical activity; Total 5 days
Experimental: Aerobic exercise

n=15; receiving supervised aerobic exercise for 60-90 minutes/day at 65% of heart rate reserve; Total 5 days
Behavioral: Aerobic exercise

Participants will perform supervised aerobic exercise for 60-90 minutes per day at 65% of heart rate reserve on 5 consecutive days.
Experimental: Prolonged fasting

n=15; following a prolonged fasting protocol providing approximately 600 kcal/day; Total 5 days
Behavioral: Prolonged fasting

Participants will follow a medically supervised prolonged fasting protocol providing approximately 600 kcal/day for five consecutive days.
Experimental: Aerobic exercise + prolonged fasting

n=15; receiving supervised aerobic exercise for 60-90 minutes/day at 65% of heart rate reserve and prolonged fasting providing approximately 600 kcal/day; Total 5 days
Behavioral: Aerobic exercise

Participants will perform supervised aerobic exercise for 60-90 minutes per day at 65% of heart rate reserve on 5 consecutive days.

Behavioral: Prolonged fasting

Participants will follow a medically supervised prolonged fasting protocol providing approximately 600 kcal/day for five consecutive days.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
iBAT adipocyte composition and gene expression (snRNA-seq)
Time Frame: 1 week

Change in adipocyte subpopulations and gene expression in dorsocervical iBAT assessed by single-nucleus RNA sequencing (snRNA-seq)
1 week

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
iBAT mitochondrial respiration (Oroboros O2k).
Time Frame: 1 week

Change in mitochondrial respiration in dorsocervical iBAT assessed by high-resolution respirometry.
1 week
iBAT protein expression (Western blot)
Time Frame: 1 week

Change in protein expression in dorsocervical iBAT assessed by Western blot, including markers related to thermogenesis and mitochondrial function.
1 week
Total Body Fat Mass
Time Frame: 5 weeks

Change in total body fat mass (kg) from baseline, assessed by dual-energy X-ray absorptiometry (DXA).
5 weeks
Body Fat Percentage
Time Frame: 5 weeks

Change in total body fat percentage (%) from baseline, assessed by dual-energy X-ray absorptiometry (DXA).
5 weeks
Resting Metabolic Rate
Time Frame: 5 weeks

Change in resting metabolic rate (kcal/day) from baseline, assessed by indirect calorimetry.
5 weeks
Cardiorespiratory Fitness - Peak Oxygen Uptake (VO₂peak)
Time Frame: 5 weeks

Change from baseline in peak oxygen uptake (VO₂peak; mL/kg/min), assessed during exercise testing with breath-by-breath gas exchange analysis.
5 weeks
LDL Cholesterol
Time Frame: 5 weeks

Change in fasting LDL cholesterol (mg/dL) from baseline, assessed in blood samples.
5 weeks
Urinary Urea Nitrogen
Time Frame: 5 weeks

Change from baseline in urinary urea nitrogen (UUN) concentration (mg/dL), assessed in urine samples as a marker of protein metabolism.
5 weeks
Gut microbiota
Time Frame: 5 weeks

Change in gut microbiota composition assessed in fecal samples.
5 weeks
Fat-Free Mass
Time Frame: 5 weeks

Change in total fat-free mass (kg) from baseline, assessed by dual-energy X-ray absorptiometry (DXA).
5 weeks
Visceral Adipose Tissue (VAT) Fat Mass
Time Frame: 5 weeks

Change in visceral adipose tissue (VAT) fat mass (g) from baseline, assessed by dual-energy X-ray absorptiometry (DXA).
5 weeks
Subcutaneous Adipose Tissue (SAT) Fat Mass
Time Frame: 5 weeks

Change in subcutaneous adipose tissue (SAT) fat mass (g) from baseline, assessed by dual-energy X-ray absorptiometry (DXA).
5 weeks
Fat Oxidation Rate at Rest
Time Frame: 5 weeks

Change in resting fat oxidation rate (g/min) from baseline, calculated from oxygen consumption (VO₂) and carbon dioxide production (VCO₂) measured by indirect calorimetry.
5 weeks
Carbohydrate Oxidation Rate at Rest
Time Frame: 5 weeks

Change in resting carbohydrate oxidation rate (g/min) from baseline, calculated from oxygen consumption (VO₂) and carbon dioxide production (VCO₂) measured by indirect calorimetry.
5 weeks
HDL Cholesterol
Time Frame: 5 weeks

Change in fasting HDL cholesterol (mg/dL) from baseline, assessed in blood samples.
5 weeks
Fasting Glucose
Time Frame: 5 weeks

Change in fasting blood glucose (mg/dL) from baseline.
5 weeks
Fasting Insulin
Time Frame: 5 weeks

Change in fasting insulin concentration (µIU/mL) from baseline, assessed in blood samples.
5 weeks
Triglycerides
Time Frame: 5 weeks

Change in fasting triglyceride concentration (mg/dL) from baseline, assessed in blood samples.
5 weeks
C-Reactive Protein (CRP)
Time Frame: 5 weeks

Change in C-reactive protein concentration (mg/L) from baseline, assessed in blood samples.
5 weeks
Fat Oxidation During Exercise
Time Frame: 5 weeks

Change from baseline in fat oxidation rate (g/min) during exercise, estimated by indirect calorimetry using a COSMED Quark metabolic cart.
5 weeks
Carbohydrate Oxidation During Exercise
Time Frame: 5 weeks

Change from baseline in carbohydrate oxidation rate (g/min) during exercise, estimated by indirect calorimetry using a COSMED Quark metabolic cart.
5 weeks

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Universidad de Almeria

Collaborators

Collaborators

An organization other than the sponsor that provides support for a clinical study. This support may include activities related to funding, design, implementation, data analysis, or reporting.
Leiden University Medical Center
ETH Zurich (Switzerland)
Buchinger Wilhelmi Development & Holding GmbH

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
September 1, 2027

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
September 1, 2029

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
September 1, 2029

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
September 9, 2026

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 17, 2026

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
September 23, 2026

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
September 23, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
September 17, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
September 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • PID2025-173649OB-I00

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Sharing Time Frame

5 years after publishing the data

IPD Sharing Access Criteria

Everybody

IPD Sharing Supporting Information Type

  • STUDY_PROTOCOL
  • ICF
  • CSR

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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