How sex hormones affect the age- and sex-related benefits of a low-calorie diet

Is this trial a fit for you?

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

The study enrolls healthy adults with BMI 27–45 kg/m2 and places them on a controlled diet program with an initial maintenance phase followed by a supervised weight-loss (calorie-restricted) phase. Participants are grouped by sex and age (younger ≤40 and older 55–65) with older women split by menopausal status and HRT use, allowing comparison across five cohorts. Researchers will measure body composition, blood glucose and metabolic markers, and sex hormone levels to link hormonal status with changes in fat loss and metabolic outcomes. People on excluded medications or with disqualifying health conditions are screened out to reduce confounding effects.

Why it matters

Who can join: the full rules

Inclusion criteria

* Adults (aged over 18years) who are healthy but overweight/obese (BMI 27-45kg/m2) males and females as:
* 15 women (age 40 or less years)
* 15 men (age 40 or less years)
* 15 women (age 55-65 years) in menopause\*; not taking Hormone Replacement Therapy (HRT)
* 15 men (age 55-65 years)
* 15 women (age 55-65 years) in menopause; taking HRT\*\*

  * menopause definition is no menstrual period for 12 months \*\*HRT inclusion criteria - women will have continuously taken oestrogen HRT for 24 months

Exclusion criteria:

Potential volunteers will be asked to fill in a health questionnaire at the screening visit to assess their suitability for the study. This information will allow us to exclude participants.

Medication exclusion criteria, current use :-

• weight loss medication (e.g. GLP agonists), β-blockers, antihistamines, antipsychotics, benzodiazepines, barbiturates, melatonin, Ritalin, modafinil, soporifics, hypnotics, antiepileptic drugs, diabetes medication (e.g. metformin or insulin).

Self-reported medical exclusion criteria:

* Females who are planning to be pregnant, are pregnant or are breastfeeding
* Anyone with coeliac disease or gluten intolerance or food allergy
* Anyone with diagnosed T1 or T2 diabetes
* Anyone suffering from a psychiatric disorder or any type of substance abuse

Other exclusion criteria

* Anyone following a vegetarian or vegan diet
* Anyone currently following a weight loss programme (that may be affecting lifestyle, physical activity \& diet) or undergone gastric band/reduction surgery; including GLP agonist (e.g. Semaglutide injection, Ozempic®).
* Anyone currently participating in another research study
* Anyone with unsuitable veins for blood sampling
* Anyone who is unable to fluently speak, read and understand English
* Anyone who is unable to comply to an alcohol-free diet for 6 weeks
* Anyone unable to give fully informed consent

Where it's running

• Rowett Institute, University of Aberdeen
  Aberdeen, United Kingdom Recruiting

Study contacts

• Principal investigator: Alexandra M Johnstone, Professor — Rowett Institute, University of Aberdeen
• Study coordinator: Alexandra M. Johnstone, Professor
• Email: alex.johnstone@abdn.ac.uk
• Phone: 01224 438614

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How to take part

1. Review the eligibility criteria above with your treating physician.
2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.