ObesityMOTORBATNCT05468151
Cold Acclimation as a Modulator of Brown Adipose Tissue Function in Adults With Obesity
A study testing Cold acclimation and Acute cold exposure in people with Obesity, run by Turku University Hospital at 1 site in Finland.
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 45 yearsHealthy volunteers can take part
- Conditions the study is for
- Obesity
- What is being tested?
- Cold acclimation and Acute cold exposure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 45 participants
- Where
- 1 siteFinland
- Study dates
- 25 Jul 2022to 1 Dec 2026
- 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 to 45 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- 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)
Who cannot join
- 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
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- 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.
Trial locations and contacts
1 site in 1 country.
About this study
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.
Read the 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.
- Conditions
- Obesity
- Being tested
- Cold acclimation, Intervention Control group - volunteers with obesity, Acute cold exposure
- Medical subject headings
- Obesity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Cold acclimationOther
Also called Cold immersion
The cold water immersions will last 30-60 minutes per day and the volunteers will undergo 2-3 cold immersions per week.
Intervention Control group - volunteers with obesityOther
Participants with obesity in the control group will undergo PET/CT scans at baseline and 12 weeks after the first scan.
Acute cold exposureOther
All participants (lean and with obesity) will undergo PET/scans after 2 hours of cold exposure to investigate BAT perfusion and BAT glucose uptake.
| Study group | Role | What they receive |
|---|---|---|
| Cold acclimation protocol | Experimental | 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. Receives: Other: Cold acclimation |
| Acute cold exposure - control volunteers with obesity | Other | 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. Receives: Other: Intervention Control group - volunteers with obesity |
| Acute cold exposure - lean controls | Other | 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. Receives: Other: Acute cold exposure |
What is being measured
The primary outcome is the main question the study is designed to answer.
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.
Measured: After at least 12 weeks of cold acclimation
Secondary outcomes (2)
Brown adipose tissue glucose uptake
BAT glucose uptake will be measured after cold exposure using Fluorodeoxyglucose (18F-FDG).
Measured: 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).
Measured: After at least 12 weeks of cold acclimation
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted21 Jul 2022
- Study start25 Jul 2022
- Primary completion20 Dec 2024
- Study completion1 Dec 2026 (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
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 45 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Turku University Hospital
- Sponsor type
- Other government
- Collaborators
- University of Turku, University of Barcelona, University of Ottawa
- Responsible party
- Principal investigator, Kirsi Virtanen, Turku University Hospital
- Investigators
- Kirsi A Virtanen, Principal investigator, Turku University HospitalFrancisco Acosta, PhD, Study director, Turku PET CentreMueez U-Din, PhD, Study director, Turku PET Centre
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT05468151
- Sponsor's protocol ID
- T138/2022
- Acronym
- MOTORBAT
- Status last verified
- May 2026
- First submitted
- 19 Jul 2022
- Last updated
- 11 May 2026
- Results posted
- 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 11 May 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Cold Acclimation as a Modulator of Brown Adipose Tissue Function in Adults With Obesity
- ClinicalTrials.gov ID
- NCT05468151
- Acronym / sponsor ID
- MOTORBAT / T138/2022
- Conditions
- Obesity
- Study type
- Interventional
- Recruitment status
- Active, not recruiting
- Enrolment
- 45 participants (estimated)
- Lead sponsor
- Turku University HospitalOther government
- Collaborators
- University of Turku, University of Barcelona, University of Ottawa
- Study start
- 25 Jul 2022 (actual)
- Primary completion
- 20 Dec 2024 (actual)
- Study completion
- 1 Dec 2026 (estimated)
- First posted
- 21 Jul 2022 (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.
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.
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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Cold acclimation protocol | Experimental | Other: Cold acclimationParticipants 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. |
| Acute cold exposure - control volunteers with obesity | Other | Other: Intervention Control group - volunteers with obesityPET/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. |
| Acute cold exposure - lean controls | Other | Other: Acute cold exposurePET/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. |
Who may qualify
- Ages
- 18 to 45 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (5 listed)
- 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)
Key exclusion criteria (13 listed)
- 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)
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 |
|---|---|---|
| Cold acclimationAlso: Cold immersionThe cold water immersions will last 30-60 minutes per day and the volunteers will undergo 2-3 cold immersions per week. | Other | Cold acclimation protocol |
| Intervention Control group - volunteers with obesityParticipants with obesity in the control group will undergo PET/CT scans at baseline and 12 weeks after the first scan. | Other | Acute cold exposure - control volunteers with obesity |
| Acute cold exposureAll participants (lean and with obesity) will undergo PET/scans after 2 hours of cold exposure to investigate BAT perfusion and BAT glucose uptake. | Other | Acute cold exposure - lean controls |
Primary outcome
Brown adipose tissue perfusion
Time frame: After at least 12 weeks of cold acclimation
BAT perfusion will be measured using 15O-O2 and 15O-H2O PET-CT, at room temperature and after 2 hours of cold exposure.
2 secondary outcomes
Brown adipose tissue glucose uptake
Time frame: After at least 12 weeks of cold acclimation
Brown adipose tissue NEFA uptake
Time frame: After at least 12 weeks of cold acclimation
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 11 May 2026.
- Individual participant dataSharing planned: No
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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. This study is not recruiting at the moment.
Kirsi A Virtanen principal investigator
Turku University Hospital
Francisco Acosta, PhD study director
Turku PET Centre
Mueez U-Din, PhD study director
Turku PET Centre
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Cold acclimation and Acute cold exposure in people with Obesity, run by Turku University Hospital at 1 site in Finland.
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 5 inclusion and 13 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: under way, not looking for participants, as of the sponsor's last update on 11 May 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Finland. Whether a site is taking part right now should be confirmed with that site. See every site.
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?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Brown adipose tissue perfusion (time frame: After at least 12 weeks of cold acclimation). 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 11 May 2026.