Brown Adipose TissueICEBATHNCT07048405
Intermittent Cold Exposure and Brown Adipose Tissue Hyperplasia
A study testing Cooling, Biopsies and Injection of 18F-FDG in people with Brown Adipose Tissue and Cold Exposure, run by University of Edinburgh at 1 site in United Kingdom.
Trial summary
This clinical trial explores how repeated short-term cold exposure impacts the molecular and physiological function of brown adipose tissue (BAT), a thermogenic organ associated with improved cardiometabolic health. Read more about this study
- Who is it for?
- Ages 18 to 40 yearsHealthy volunteers can take part
- Conditions the study is for
- Brown Adipose Tissue, Cold Exposure, 18F-FDG PET/CT
- What is being tested?
- Cooling, Biopsies and Injection of 18F-FDG
- Type of treatment
- Pill or oral medicine, Injection or infusion, Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 12 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- 1 May 2025to Jul 2027
- 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 40 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Aged 18-40 years
- Body mass index 18.5-25 kg/m2
- Weight change of less than 5% in the past 6 months
- No acute or chronic medical conditions
- On no regular medications (other than contraceptives in female participants)
- No claustrophobia
Show all 10Show fewer
- Alcohol intake ≤14 units/ week
- Screening blood tests within acceptable limits (of no clinical significance)
- Not currently pregnant, lactating or breastfeeding (female participants only)
- Ability to provide informed consent.
Who cannot join
- Not meeting inclusion criteria
- Contra-indication to PET/CT scan
- Allergy to local anaesthetic
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United Kingdom1 site, 1 recruiting
- Recruiting
Royal Infirmary of Edinburgh
Edinburgh
María Paula Huertas Caycedo, 01312429196, m.p.huertas-caycedo@sms.ed.ac.uk
About this study
Official title: Investigating the Cellular Heterogeneity of Human Brown Adipose Tissue and Its (Patho)Physiological Regulation
This clinical trial explores how repeated short-term cold exposure impacts the molecular and physiological function of brown adipose tissue (BAT), a thermogenic organ associated with improved cardiometabolic health. While intermittent cold exposure has been shown to increase BAT activity and mass, as measured by fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) scans, the molecular adaptations within BAT and other thermogenic tissues including skeletal muscle and white adipose tissue (WAT) remain poorly understood.
Healthy adults aged 18 to 40 years (6 males and 6 females) will participate in a 10-day cold acclimation protocol (2 hours per day using water-perfused cooling blankets). The primary objective is to determine how cold exposure alters cellular heterogeneity and gene expression in BAT, WAT, and skeletal muscle.
Participants will undergo baseline assessments, including measurements of energy expenditure, core and skin temperature, muscle activity, and blood sampling, each performed in both warm and cold conditions. These assessments will be followed by dynamic total-body PET/CT imaging during cold exposure and tissue biopsies from BAT, subcutaneous WAT, and skeletal muscle. These procedures will be repeated after the cold acclimation protocol to evaluate physiological and molecular changes. Additional outcomes include changes in energy expenditure, cold tolerance, and immune cell responses induced by cold exposure.
Read the detailed description
Twelve healthy adults aged 18-40 years old (6 female, 6 male) will:
- Attend baseline visits in both warm and cold conditions for blood sampling, measurement of energy expenditure, skin and core temperature, muscle activity. This will be followed by dynamic total-body 18F-FDG PET/CT scan during cold exposure.
- Undergo biopsies of BAT (supraclavicular), skeletal muscle (vastus lateralis), and subcutaneous WAT (periumbilical) under local anesthesia.
- Complete 10 consecutive days of cold acclimation (2 hours per day) using water-perfused cooling blankets.
- Return for follow-up assessments, including repeat blood sampling, energy expenditure, temperature measurements, PET/CT imaging, and tissue biopsies to evaluate post-acclimation changes.
- Conditions
- Brown Adipose Tissue, Cold Exposure, 18F-FDG PET/CT
- Being tested
- Cooling, Biopsies, Injection of 18F-FDG, Indirect calorimetry, Electromyogram
- Keywords
- Brown Adipose Tissue, Cold Exposure, 18F-FDG PET/CT
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
CoolingOther
Participants will undergo cold exposure during the baseline and final visits (2.5 hours each visit), as well as throughout the 10-day cold acclimation period (2 hours per day). This will be achieved using water-perfused blankets set to individualized temperatures, selected to elicit comparable physiological responses across participants.
BiopsiesProcedure or surgery
Also called brown adipose tissue biopsy, white adipose tissue biopsy, skeletal muscle biopsy
Under local anesthesia, biopsies will be obtained from the following sites:
- Brown adipose tissue from the supraclavicular (collarbone) region, guided by computed tomography (CT).
- White adipose tissue from the abdominal (periumbilical) area.
- Skeletal muscle from the outer thigh, specifically the vastus lateralis.
These biopsies will be performed both before and after the 10-day cold acclimation protocol.
Injection of 18F-FDGRadiation
Intravenous injection of 18F-FDG will be performed after 2 hours of cold exposure. This will be followed by a 30min dynamic total PET/CT scan while cold exposed using water-perfused blankets. These procedures will take place before and after the 10 day-cold acclimation protocol.
Indirect calorimetryOther
Participants will rest quietly while oxygen consumption and carbon dioxide production are continuously recorded using a indirect calorimeter. These data will be used to calculate energy expenditure and respiratory exchange ratio. This procedure will take place before and after the 10 day-cold acclimation protocol.
ElectromyogramOther
Skin surface electrodes will be placed on major skeletal muscles to measure shivering and muscle activity during both warm and cold conditions. This procedure will take place before and after the 10 day-cold acclimation protocol.
Core and skin temperature monitoringOther
Participants will ingest an electronic capsule that wirelessly and continuously monitors core body temperature. This procedure will be conducted before and after the 10-day cold acclimation protocol.
Additionally, wireless temperature sensors will placed at multiple standardized sites on the body to measure skin temperature. This procedure will be performed before, during, and after the 10-day cold acclimation protocol.
| Study group | Role | What they receive |
|---|---|---|
| Healthy normal weight subjects | Experimental | Not described Receives: Other: Cooling; Procedure: Biopsies; Radiation: Injection of 18F-FDG; Other: Indirect calorimetry; Other: Electromyogram; Other: Core and skin temperature monitoring |
What is being measured
The primary outcome is the main question the study is designed to answer.
Tissue transcriptional changes derived from cold exposure
We will be analysing and comparing gene expression from nuclei extracted from BAT, WAT and skeletal muscle before and after cold the 10-day cold acclimation protocol.
Measured: 1 year
Secondary outcomes (4)
Changes in brown adipose tissue activity/mass before and after cold acclimation protocol
BAT activity/mass will be measured using the glucose analogue 18-FDG radiotracer combine with PET/CT.
Measured: year after
Energy expenditure
Energy expenditure measured with indirect calorimetry before and after cold acclimation protocol to evaluated any changes in response to intermittent cold exposure.
Measured: year after
Skin and core temperature
Measurement of skin and core temperature before and after the cold acclimation protocol
Measured: year after
Immune cell levels
Analyse the percentage of immune cell populations before and after cold acclimation
Measured: year after
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Jul 2025
- Study start1 May 2025
- Primary completionJul 2027 (estimated)
- Study completionJul 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Brown Adipose TissueStudies 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
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 12 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Edinburgh
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07048405
- Sponsor's protocol ID
- 350117
- Other IDs
- 24/SS/0094
- Acronym
- ICEBATH
- Status last verified
- Jun 2026
- First submitted
- 6 May 2025
- Last updated
- 30 Jun 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 30 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Investigating the Cellular Heterogeneity of Human Brown Adipose Tissue and Its (Patho)Physiological Regulation
- ClinicalTrials.gov ID
- NCT07048405
- Acronym / sponsor ID
- ICEBATH / 350117
- Conditions
- Brown Adipose Tissue, Cold Exposure, 18F-FDG PET/CT
- Keywords
- Brown Adipose Tissue, Cold Exposure, 18F-FDG PET/CT
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 12 participants (estimated)
- Lead sponsor
- University of EdinburghUniversity, hospital or other
- Study start
- 1 May 2025 (actual)
- Primary completion
- Jul 2027 (estimated)
- Study completion
- Jul 2027 (estimated)
- First posted
- 2 Jul 2025 (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 clinical trial explores how repeated short-term cold exposure impacts the molecular and physiological function of brown adipose tissue (BAT), a thermogenic organ associated with improved cardiometabolic health. While intermittent cold exposure has been shown to increase BAT activity and mass, as measured by fluorodeoxyglucose (18F-FDG) uptake on positron emission tomography/computed tomography (PET/CT) scans, the molecular adaptations within BAT and other thermogenic tissues including skeletal muscle and white adipose tissue (WAT) remain poorly understood.
Healthy adults aged 18 to 40 years (6 males and 6 females) will participate in a 10-day cold acclimation protocol (2 hours per day using water-perfused cooling blankets). The primary objective is to determine how cold exposure alters cellular heterogeneity and gene expression in BAT, WAT, and skeletal muscle.
Participants will undergo baseline assessments, including measurements of energy expenditure, core and skin temperature, muscle activity, and blood sampling, each performed in both warm and cold conditions. These assessments will be followed by dynamic total-body PET/CT imaging during cold exposure and tissue biopsies from BAT, subcutaneous WAT, and skeletal muscle. These procedures will be repeated after the cold acclimation protocol to evaluate physiological and molecular changes. Additional outcomes include changes in energy expenditure, cold tolerance, and immune cell responses induced by cold exposure.
Detailed description
Twelve healthy adults aged 18-40 years old (6 female, 6 male) will:
- Attend baseline visits in both warm and cold conditions for blood sampling, measurement of energy expenditure, skin and core temperature, muscle activity. This will be followed by dynamic total-body 18F-FDG PET/CT scan during cold exposure.
- Undergo biopsies of BAT (supraclavicular), skeletal muscle (vastus lateralis), and subcutaneous WAT (periumbilical) under local anesthesia.
- Complete 10 consecutive days of cold acclimation (2 hours per day) using water-perfused cooling blankets.
- Return for follow-up assessments, including repeat blood sampling, energy expenditure, temperature measurements, PET/CT imaging, and tissue biopsies to evaluate post-acclimation changes.
Study design
- Primary purpose
- Basic science
- Allocation
- Not applicable
- Intervention model
- Single group
- Masking
- None (open label)
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Healthy normal weight subjects | Experimental | Other: Cooling, Procedure: Biopsies, Radiation: Injection of 18F-FDG, Other: Indirect calorimetry, Other: Electromyogram, Other: Core and skin temperature monitoring |
Who may qualify
- Ages
- 18 to 40 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (10 listed)
- Aged 18-40 years
- Body mass index 18.5-25 kg/m2
- Weight change of less than 5% in the past 6 months
- No acute or chronic medical conditions
- On no regular medications (other than contraceptives in female participants)
Key exclusion criteria (3 listed)
- Not meeting inclusion criteria
- Contra-indication to PET/CT scan
- Allergy to local anaesthetic
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 |
|---|---|---|
| CoolingParticipants will undergo cold exposure during the baseline and final visits (2.5 hours each visit), as well as throughout the 10-day cold acclimation period (2 hours per day). This will be achieved using water-perfused blankets set to individualized temperatures, selected to elicit comparable physiological responses across participants. | Other | Healthy normal weight subjects |
| BiopsiesAlso: brown adipose tissue biopsy, white adipose tissue biopsy, skeletal muscle biopsyUnder local anesthesia, biopsies will be obtained from the following sites: * Brown adipose tissue from the supraclavicular (collarbone) region, guided by computed tomography (CT). * White adipose tissue from the abdominal (periumbilical) area. * Skeletal muscle from the outer thigh, specifically the vastus lateralis. These biopsies will be performed both before and after the 10-day cold acclimation protocol. | Procedure or surgery | Healthy normal weight subjects |
| Injection of 18F-FDGIntravenous injection of 18F-FDG will be performed after 2 hours of cold exposure. This will be followed by a 30min dynamic total PET/CT scan while cold exposed using water-perfused blankets. These procedures will take place before and after the 10 day-cold acclimation protocol. | Radiation | Healthy normal weight subjects |
| Indirect calorimetryParticipants will rest quietly while oxygen consumption and carbon dioxide production are continuously recorded using a indirect calorimeter. These data will be used to calculate energy expenditure and respiratory exchange ratio. This procedure will take place before and after the 10 day-cold acclimation protocol. | Other | Healthy normal weight subjects |
| ElectromyogramSkin surface electrodes will be placed on major skeletal muscles to measure shivering and muscle activity during both warm and cold conditions. This procedure will take place before and after the 10 day-cold acclimation protocol. | Other | Healthy normal weight subjects |
| Core and skin temperature monitoringParticipants will ingest an electronic capsule that wirelessly and continuously monitors core body temperature. This procedure will be conducted before and after the 10-day cold acclimation protocol. Additionally, wireless temperature sensors will placed at multiple standardized sites on the body to measure skin temperature. This procedure will be performed before, during, and after the 10-day cold acclimation protocol. | Other | Healthy normal weight subjects |
Primary outcome
Tissue transcriptional changes derived from cold exposure
Time frame: 1 year
We will be analysing and comparing gene expression from nuclei extracted from BAT, WAT and skeletal muscle before and after cold the 10-day cold acclimation protocol.
4 secondary outcomes
Changes in brown adipose tissue activity/mass before and after cold acclimation protocol
Time frame: year after
Energy expenditure
Time frame: year after
Skin and core temperature
Time frame: year after
Immune cell levels
Time frame: year after
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 30 Jun 2026.
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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.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Cooling, Biopsies and Injection of 18F-FDG in people with Brown Adipose Tissue and Cold Exposure, run by University of Edinburgh at 1 site in United Kingdom.
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 10 inclusion and 3 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: looking for participants now, as of the sponsor's last update on 30 Jun 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 United Kingdom. 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?
Contact María Paula Huertas Caycedo (01312429196, m.p.huertas-caycedo@sms.ed.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Tissue transcriptional changes derived from cold exposure (time frame: 1 year). 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 30 Jun 2026.