Seasonal Variation in Energy Expenditure, Water Turnover, and Physical Activity in Adults

NCT07856316 | Not Yet Recruiting

• 1 other identifier: 12558330
• Study Type: observational
• Target: 30
• Locations: 1 country
• Sites: 1

Brief 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. 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.

Conditions

Energy Expenditure; Physical Activity

Keywords

Seasonal variation; Total energy expenditure; Physical activity; Ambient temperature; Water turnover

Outcome Measures

Primary Outcomes (1)

• 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.

  Each approximately 14-day measurement period in winter and summer

Secondary Outcomes (2)

• Change in Physical Activity Between Winter and Summer

  Continuously over each approximately 14-day measurement period in winter and summer

• Change in Water Turnover Between Winter and Summer

  Each approximately 14-day measurement period in winter and summer

Study Arms (1)

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.

Other: Seasonal Environmental Exposure

Interventions

Seasonal Environmental Exposure OTHER

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.

Healthy Adults

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)
• Sampling Method: Non-Probability Sample

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.

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• University of Aberdeen: lead

Study Sites (1)

University of Aberdeen, School of Biological Sciences, Zoology Building

Aberdeen, Scotland, AB24 2TZ, United Kingdom

Location

Biospecimen

Retention: SAMPLES WITH DNA

Urine samples collected for doubly labelled water analysis and related quality control and repeat analyses. Samples will not be used for genetic analysis and will be destroyed after completion of the planned analyses and dissemination of study findings.

MeSH Terms

Conditions

Motor Activity

Condition Hierarchy (Ancestors)

Behavior

Study Officials

• John R Speakman

  University of Aberdeen

  PRINCIPAL INVESTIGATOR

• Catherine Hambly

  University of Aberdeen

  STUDY DIRECTOR

• Sharon Mitchell

  University of Aberdeen

  STUDY DIRECTOR

Central Study Contacts

HUIHUI MEI

CONTACT

+447345185714; h.mei.25@abdn.ac.uk

Study Design

• Study Type: observational
• Observational Model: COHORT
• Time Perspective: PROSPECTIVE
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: September 23, 2026
• First Posted: October 2, 2026
• Study Start (Estimated): December 1, 2026
• Primary Completion (Estimated): April 1, 2028
• Study Completion (Estimated): April 1, 2028
• Last Updated: October 2, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will share

Locations

GB (1)