Energy ExpenditureNCT07856316
Seasonal Variation in Energy Expenditure, Water Turnover, and Physical Activity in Adults
An observational study of Energy Expenditure and Physical Activity, run by University of Aberdeen at 1 site in United Kingdom.
Trial summary
This prospective observational study will investigate seasonal variation in total energy expenditure, water turnover, and physical activity in healthy adults living in or near Aberdeen, Scotland. Participants will complete two approximately 14-day measurement periods, one in winter and one in summer. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Energy Expenditure, Physical Activity
- What is being tested?
- Seasonal Environmental Exposure
- How many people
- 30 participants
- Where
- 1 siteUnited Kingdom
- Study dates
- Dec 2026to Apr 2028
- Phase
- Observational
- 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 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Healthy adult volunteers aged 18-50 years living in or near Aberdeen, Scotland. Participants will be recruited from the general adult population through open advertisement and must be available to complete both winter and summer measurement periods. Recruitment will aim for approximately balanced representation of males and females.
Who may be able to join
- Healthy adults aged 18-50 years Body mass index (BMI) of 18.5-29.9 kg/m² Available to participate in both winter (January/February) and summer (July/August) measurement periods Resident in or near Aberdeen, or spending most of the year in Scotland during the study period
Who cannot join
- Any condition limiting normal daily physical activity Engagement in high-intensity training, including professional athletes History of bariatric surgery, current weight-loss interventions, or significant recent weight change (>5 kg in the previous 6 months) Pregnancy, breastfeeding, planning pregnancy, irregular menstrual cycles, or menopause Any medical condition that may affect metabolism, physical activity, water balance, or study safety, including diabetes, uncontrolled thyroid disease, significant heart or kidney disease, or respiratory disease that limits normal activity Any psychiatric condition that may affect participation, daily activity, appetite, or ability to follow study procedures Use of medications or treatments that may significantly affect metabolism, appetite, body weight, or physical activity, including weight-loss medications, corticosteroids, diuretics, or stimulant medications Inability to provide informed consent Any condition judged by the investigators to compromise participant safety or data quality
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
University of Aberdeen, School of Biological Sciences, Zoology Building
Aberdeen, Scotland, AB24 2TZ
HUIHUI MEI, +447345185714, h.mei.25@abdn.ac.uk
About this study
Official title: Impacts of Seasonal Environmental Variation on Energy Expenditure, Water Turnover, and Physical Activity
This prospective observational study will investigate seasonal variation in total energy expenditure, water turnover, and physical activity in healthy adults living in or near Aberdeen, Scotland. Participants will complete two approximately 14-day measurement periods, one in winter and one in summer. Total energy expenditure and water turnover will be assessed using the doubly labelled water method, while physical activity and personal environmental exposure will be measured using wearable devices. The study will examine within-person differences between winter and summer and explore whether environmental factors, including ambient temperature, daylight, and sunlight exposure, are associated with changes in energy expenditure, water turnover, and physical activity.
Read the detailed description
The study uses a prospective repeated-measures design in which the same participants are assessed during winter and summer under free-living conditions. Healthy adults aged 18-50 years will be recruited from Aberdeen and the surrounding area. Participants will complete one approximately 14-day monitoring period in each season.
During each study period, total energy expenditure and water turnover will be assessed using doubly labelled water. Physical activity will be monitored using an accelerometer, and personal environmental exposure will be assessed using wearable temperature sensors and GPS-based location monitoring. Anthropometry, body composition, blood pressure, heart rate, and lung function will also be measured, and dietary intake will be assessed using 24-hour dietary recalls.
The primary analyses will compare measurements within individuals between winter and summer. Associations between environmental exposure, physical activity, total energy expenditure, and water turnover will also be examined. The study is observational; seasonal and environmental exposures are not assigned by the investigators.
- Conditions
- Energy Expenditure, Physical Activity
- Being tested
- Seasonal Environmental Exposure
- Keywords
- Seasonal variation, Total energy expenditure, Physical activity, Ambient temperature, Water turnover
- Medical subject headings
- Motor Activity
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Seasonal Environmental ExposureOther
Participants will be observed under naturally occurring winter and summer environmental conditions. Environmental exposures of interest include personal ambient temperature, time spent outdoors, relative humidity, and daylight/sunlight conditions. Personal ambient temperature and outdoor exposure will be characterised during each approximately 14-day measurement period using wearable temperature sensors and GPS-based monitoring. Relative humidity and daylight/sunlight conditions will be characterised using regional meteorological and environmental data. These exposures are not assigned or manipulated by the investigators and will be examined in relation to total energy expenditure, water turnover, and physical activity.
| Study group | Role | What they receive |
|---|---|---|
| Healthy Adults | Healthy adults aged 18-50 years living in or near Aberdeen, Scotland. All participants will complete two approximately 14-day free-living measurement periods, one in winter and one in summer. Seasonal and environmental exposures are observed under natural conditions and are not assigned by the investigators. Receives: Other: Seasonal Environmental Exposure |
What is being measured
The primary outcome is the main question the study is designed to answer.
Change in Total Energy Expenditure Between Winter and Summer
Within-participant difference in mean daily total energy expenditure between the winter and summer measurement periods. Total energy expenditure will be measured using the doubly labelled water method and expressed in MJ/day.
Measured: Each approximately 14-day measurement period in winter and summer
Secondary outcomes (2)
Change in Physical Activity Between Winter and Summer
Within-participant difference in physical activity between the winter and summer measurement periods. Physical activity will be assessed using accelerometry, including overall activity level and time spent at different activity intensities.
Measured: Continuously over each approximately 14-day measurement period in winter and summer
Change in Water Turnover Between Winter and Summer
Within-participant difference in mean daily water turnover between the winter and summer measurement periods. Water turnover will be estimated from isotope elimination using the doubly labelled water method.
Measured: Each approximately 14-day measurement period in winter and summer
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Oct 2026
- Study startDec 2026 (estimated)
- Primary completionApr 2028 (estimated)
- Study completionApr 2028 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Energy ExpenditureStudies 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
- Observational
- Observational model
- Cohort
- Time perspective
- Prospective
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Aberdeen
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
- Investigators
- John R Speakman, Principal investigator, University of AberdeenCatherine Hambly, Study director, University of AberdeenSharon Mitchell, Study director, University of Aberdeen
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07856316
- Sponsor's protocol ID
- 12558330
- Status last verified
- Sep 2026
- First submitted
- 23 Sep 2026
- Last updated
- 2 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes: Selected anonymised individual participant data related to doubly labelled water measurements may be shared through a DLW research database for future ethically approved energy expenditure research, only for participants who have provided specific consent. The full study dataset and directly identifiable participant information will not be shared.
Study at a glance
From the registry record, last updated by the sponsor on 2 Oct 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Impacts of Seasonal Environmental Variation on Energy Expenditure, Water Turnover, and Physical Activity
- ClinicalTrials.gov ID
- NCT07856316
- Acronym / sponsor ID
- 12558330
- Conditions
- Energy Expenditure, Physical Activity
- Keywords
- Seasonal variation, Total energy expenditure, Physical activity, Ambient temperature, Water turnover
- Study type
- Observational
- Recruitment status
- Not yet recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- University of AberdeenUniversity, hospital or other
- Study start
- Dec 2026 (estimated)
- Primary completion
- Apr 2028 (estimated)
- Study completion
- Apr 2028 (estimated)
- First posted
- 2 Oct 2026 (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 prospective observational study will investigate seasonal variation in total energy expenditure, water turnover, and physical activity in healthy adults living in or near Aberdeen, Scotland. Participants will complete two approximately 14-day measurement periods, one in winter and one in summer. Total energy expenditure and water turnover will be assessed using the doubly labelled water method, while physical activity and personal environmental exposure will be measured using wearable devices. The study will examine within-person differences between winter and summer and explore whether environmental factors, including ambient temperature, daylight, and sunlight exposure, are associated with changes in energy expenditure, water turnover, and physical activity.
Detailed description
The study uses a prospective repeated-measures design in which the same participants are assessed during winter and summer under free-living conditions. Healthy adults aged 18-50 years will be recruited from Aberdeen and the surrounding area. Participants will complete one approximately 14-day monitoring period in each season.
During each study period, total energy expenditure and water turnover will be assessed using doubly labelled water. Physical activity will be monitored using an accelerometer, and personal environmental exposure will be assessed using wearable temperature sensors and GPS-based location monitoring. Anthropometry, body composition, blood pressure, heart rate, and lung function will also be measured, and dietary intake will be assessed using 24-hour dietary recalls.
The primary analyses will compare measurements within individuals between winter and summer. Associations between environmental exposure, physical activity, total energy expenditure, and water turnover will also be examined. The study is observational; seasonal and environmental exposures are not assigned by the investigators.
Study design
- Observational model
- Cohort
- Time perspective
- Prospective
- Number of arms
- 1
| Arm | Type | Receives |
|---|---|---|
| Healthy Adults | – | Other: Seasonal Environmental ExposureHealthy adults aged 18-50 years living in or near Aberdeen, Scotland. All participants will complete two approximately 14-day free-living measurement periods, one in winter and one in summer. Seasonal and environmental exposures are observed under natural conditions and are not assigned by the investigators. |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Healthy adult volunteers aged 18-50 years living in or near Aberdeen, Scotland. Participants will be recruited from the general adult population through open advertisement and must be available to complete both winter and summer measurement periods. Recruitment will aim for approximately balanced representation of males and females.
Key inclusion criteria (1 listed)
- Healthy adults aged 18-50 years Body mass index (BMI) of 18.5-29.9 kg/m² Available to participate in both winter (January/February) and summer (July/August) measurement periods Resident in or near Aberdeen, or spending most of the year in Scotland during the study period
Key exclusion criteria (1 listed)
- Any condition limiting normal daily physical activity Engagement in high-intensity training, including professional athletes History of bariatric surgery, current weight-loss interventions, or significant recent weight change (>5 kg in the previous 6 months) Pregnancy, breastfeeding, planning pregnancy, irregular menstrual cycles, or menopause Any medical condition that may affect metabolism, physical activity, water balance, or study safety, including diabetes, uncontrolled thyroid disease, significant heart or kidney disease, or respiratory disease that limits normal activity Any psychiatric condition that may affect participation, daily activity, appetite, or ability to follow study procedures Use of medications or treatments that may significantly affect metabolism, appetite, body weight, or physical activity, including weight-loss medications, corticosteroids, diuretics, or stimulant medications Inability to provide informed consent Any condition judged by the investigators to compromise participant safety or data quality
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 |
|---|---|---|
| Seasonal Environmental ExposureParticipants will be observed under naturally occurring winter and summer environmental conditions. Environmental exposures of interest include personal ambient temperature, time spent outdoors, relative humidity, and daylight/sunlight conditions. Personal ambient temperature and outdoor exposure will be characterised during each approximately 14-day measurement period using wearable temperature sensors and GPS-based monitoring. Relative humidity and daylight/sunlight conditions will be characterised using regional meteorological and environmental data. These exposures are not assigned or manipulated by the investigators and will be examined in relation to total energy expenditure, water turnover, and physical activity. | Other | Healthy Adults |
Primary outcome
Change in Total Energy Expenditure Between Winter and Summer
Time frame: Each approximately 14-day measurement period in winter and summer
Within-participant difference in mean daily total energy expenditure between the winter and summer measurement periods. Total energy expenditure will be measured using the doubly labelled water method and expressed in MJ/day.
2 secondary outcomes
Change in Physical Activity Between Winter and Summer
Time frame: Continuously over each approximately 14-day measurement period in winter and summer
Change in Water Turnover Between Winter and Summer
Time frame: Each approximately 14-day measurement period in winter and summer
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 2 Oct 2026.
- Individual participant dataSharing planned: Yes. Selected anonymised individual participant data related to doubly labelled water measurements may be shared through a DLW research database for future ethically approved energy expenditure research, only for participants who have provided specific consent. The full study dataset and directly identifiable participant information will not be shared.
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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.
John R Speakman principal investigator
University of Aberdeen
Catherine Hambly study director
University of Aberdeen
Sharon Mitchell study director
University of Aberdeen
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Energy Expenditure and Physical Activity, run by University of Aberdeen 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 1 inclusion and 1 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: opening soon, as of the sponsor's last update on 2 Oct 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 HUIHUI MEI (+447345185714, h.mei.25@abdn.ac.uk), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Change in Total Energy Expenditure Between Winter and Summer (time frame: Each approximately 14-day measurement period in winter and summer). 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 2 Oct 2026.