Clinical Research Directory

Inclusion Criteria: 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 Exclusion Criteria: 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