Cold Acclimation as a Modulator of Brown Adipose Tissue Function in Adults With Obesity (MOTORBAT)

This study will investigate the effects of at least 12 weeks of weekly cold water immersions (water temperature 18ºC) on BAT perfusion in individuals with obesity. BAT oxygen uptake and tissue perfusion will be measured using 15O-O2 and 15O-H2O PET-CT, at room temperature and after cold exposure. In addition, BAT glucose uptake will be measured using 18F-FDG after 2 hours of cold exposure and BAT NEFA uptake will be analyzed using 18F-FTHA at room temperature.

To understrand the metabolic effects of BAT activation in individuals with obesity and how the cold water immersions affect the BAT perfusion in humans is critical for the development of new strategies to treat obesity and its comorbidities.

Study Overview

• Status: Active, not recruiting
• Conditions: Obesity
• Intervention / Treatment: Other: Cold acclimation; Other: Intervention Control group - volunteers with obesity; Other: Acute cold exposure

Detailed Description

Obesity is a highly prevalent non-communicable disease that effects more than 20% of the population worldwide. Brown adipose tissue (BAT) has an unique ability to dissipate the energy as heat and it has been associated with metabolic benefits. Additionally, BAT has been found to be more active in young, healthy, lean individuals and to be inactive in subjects with obesity. Some studies have shown that repeated cold acclimation can enhance BAT metabolism, which is accompanied by metabolic benefits, such as improvements in insulin sensitivity. In this study we will investigate whether 12 weeks or more of cold acclimation are sufficient to improve BAT perfusion at room temperature and after 2 hours of cold exposure, and to stimulate glucose uptake (measured using 18F-FDG) in BAT after 2 hours of cold exposure. Furthermore, changes in BAT NEFA uptake will be analyzed using 18F-FTHA at room temperature. The metabolic effects of the cold acclimation protocol will be evaluated by changes in classical cardiovascular risk markers (lipid profile, glucose and insulin) after 12 weeks. Two different control groups will be included: one will include lean, healthy participants while the other will include subjects with obesity. Both groups will undergo the BAT PET/scans protocol at room temperature and after cold exposure to investigate BAT perfusion, BAT glucose uptake and BAT NEFA uptake. The volunteers with obesity will also undergo a second evaluation 12 weeks after baseline measurements.

• Study Type: Interventional
• Enrollment (Estimated): 45
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Finland
  • Turku
    • Turku, Turku, Finland, 20520
      • Turku PET Centre

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 45 years (Adult)
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• BMI>30kg/m2 (for participants with obesity)
• BMI<25kg/m2 (for lean participants)
• Waist circumference >94 cm for men (for participants with obesity)
• Waist circumference > 80 for women (for participants with obesity)
• Glucose ≥7.8 and <11 mmol/L after OGTT (for participants with obesity)

Exclusion Criteria:

• Being regularly exposed to cold environments for the last 3 months (e.g. having a job as a ski monitor, fishmonger, woodcutter, etc.; or doing sports/leisure activities outdoors for prolonged periods of time, etc.)
• Having gone for winter/ice swimming and bathing more than once every 2 weeks during the last 3 months.
• Inability to undergo scanning (e.g., claustrophobia)
• Pregnancy
• Smoking (or use of nicotine based products)
• Hypo/hyperthyroidism
• Malignancies
• Immune disorders
• Viral or bacterial infections
• Abnormal cardiovascular status, arrhythmia and/or long QTc in ECG, abnormal cardiac murmur, previous history of cardiovascular disease
• Allergy to lidocaine or epinephrine, or other local anaesthetics
• Weight change (intentional or not) over the last 6-months > than 5% of body weight
• Any other cardiovascular, pulmonary, orthopaedic, neurologic, psychiatric or other conditions that in the opinion of the local clinician/researcher, would preclude participation and successful completion of the protocol, or that would negatively impact or mitigate participation in and completion of the protocol.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Cold acclimation protocol; Participants with obesity (n = 20) will undergo weekly cold water immersions (water temperature 18ºC, two to three times a week, 30 minutes per day) for, at least, 12 weeks. Before and after the cold acclimation period, the participants will undergo PET/CT scans at room temperature and after controlled cold exposure to investigate BAT perfusion, BAT glucose and NEFA uptakes.	Other: Cold acclimation; The cold water immersions will last 30-60 minutes per day and the volunteers will undergo 2-3 cold immersions per week.; Other Names: Cold immersion
Other: Acute cold exposure - control volunteers with obesity; PET/CT scans will be carried out after 2 hours of cold exposure The participants in this group (n = 10) will undergo PET/CT scans at baseline and 12 weeks after the first scan. The participants will undergo PET/CT scans at room temperature and after 2 hours of controlled cold exposure to investigate BAT perfusion, BAT glucose and NEFA uptakes.	Other: Intervention Control group - volunteers with obesity; Participants with obesity in the control group will undergo PET/CT scans at baseline and 12 weeks after the first scan.
Other: Acute cold exposure - lean controls; PET/CT scans will be carried out after 2 hours of cold exposure The participants in this group (lean, n = 15) will undergo PET/CT scans at room temperature and after 2 hours of controlled cold exposure to investigate BAT perfusion, BAT glucose and NEFA uptakes.	Other: Acute cold exposure; All participants (lean and with obesity) will undergo PET/scans after 2 hours of cold exposure to investigate BAT perfusion and BAT glucose uptake.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Brown adipose tissue perfusion	BAT perfusion will be measured using 15O-O2 and 15O-H2O PET-CT, at room temperature and after 2 hours of cold exposure.	After at least 12 weeks of cold acclimation

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Brown adipose tissue glucose uptake	BAT glucose uptake will be measured after cold exposure using Fluorodeoxyglucose (18F-FDG).	After at least 12 weeks of cold acclimation
Brown adipose tissue NEFA uptake	BAT NEFA uptake will be measured at room temperature using [18F]fluoro-6-thia-heptadecanoic acid (18F-FTHA).	After at least 12 weeks of cold acclimation

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Metabolic parameters	Investigate the effects of cold acclimation on blood lipids (total, LDL and HDL cholesterol and triglycerides), fasting glucose and insulin.	After at least 12 weeks of cold acclimation
Energy expenditure	To investigate the effects of cold acclimation on energy expenditure in fasting and postprandial states (after the intake of a mixed meal) using indirect calorimetry	After at least 12 weeks of cold acclimation
BAT gene expression	BAT biopsies will be collected to investigate the effects of cold acclimation on BAT gene expression.	After at least 12 weeks of cold acclimation

Collaborators and Investigators

• Sponsor: Turku University Hospital
• Collaborators: University of Turku; University of Ottawa; University of Barcelona
• Investigators: Principal Investigator: Kirsi A Virtanen, Turku University Hospital; Study Director: Francisco Acosta, PhD, Turku PET Centre; Study Director: Mueez U-Din, PhD, Turku PET Centre

Study record dates

Study Major Dates

• Study Start (Actual): July 25, 2022
• Primary Completion (Actual): December 20, 2024
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: July 19, 2022
• First Submitted That Met QC Criteria: July 19, 2022
• First Posted (Actual): July 21, 2022

Study Record Updates

• Last Update Posted (Actual): May 11, 2026
• Last Update Submitted That Met QC Criteria: May 6, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Nutrition Disorders; Overnutrition; Body Weight; Overweight; Pathological Conditions, Signs and Symptoms; Nutritional and Metabolic Diseases; Signs and Symptoms; Obesity; Diagnostic Techniques and Procedures; Diagnosis; Physiological Phenomena; Biochemical Phenomena; Chemical Phenomena; Physical Examination; Body Weights and Measures; Body Constitution; Metabolism; Body Fat Distribution; Body Composition; Adiposity
• Other Study ID Numbers: T138/2022

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
• product manufactured in and exported from the U.S.: No