RecruitingInterventional

GendAge weight loss study: sex hormones as regulators of the age- and sex-dependent benefits of caloric restriction

This study explores why age and sex might change how people lose weight when they cut calories. Researchers believe hormones, especially oestrogen, could play a role. For example, younger women often lose less weight than younger men on the same diet, but this difference disappears in older adults. By understanding these factors, the study hopes to develop more effective and tailored weight loss guidance for all adults who are overweight or obese. Participants will follow a controlled diet for 53 days, have various health checks, and contribute to research that could revolutionise dietary advice in the future.

At a glance

Status

Recruiting

Sponsor

University of Aberdeen

Enrolment target

Start

09 Jul 2025

Estimated completion

04 Feb 2028

Overweight and/or obesity

What is this study about?

Many people in the UK are overweight, which can lead to serious health problems like type 2 diabetes and heart disease. Cutting down on calories is a proven way to lose weight and body fat. However, scientists don't fully understand why some people respond differently to diets based on their age or sex.

Past research has shown that younger women sometimes lose less weight than younger men on the same diet, but this difference isn't seen in older adults. The research team thinks this might be due to oestrogen, a hormone that decreases around menopause. By studying this, they hope to figure out how age and sex hormones influence weight loss. The goal is to create better, more personal diet advice that works for everyone, no matter their age or gender.

This study will involve following a carefully planned diet and having several health checks. The information gathered will be crucial in helping to develop new dietary recommendations, ensuring that people get the most effective advice for their individual needs. It's all about making weight loss plans more successful for more people.

Key takeaways

The study investigates how age and sex hormones influence weight loss from diet.
It aims to create personalised and more effective dietary advice.
Participants will follow a controlled diet for 53 days, with all food provided.
Various health checks and measurements, including blood tests and body scans, will be conducted.
Most participants can expect to lose weight and body fat, potentially improving their health.
The study takes place at the Rowett Institute in Aberdeen.

Who may be eligible?

This study is looking for adults aged between 18 and 65 years old who are overweight or obese. You should also be in good general health to take part.

The study needs both men and women, split into two age groups: younger adults (40 years or under) and older adults (55-65 years). If you are an older woman, you must have gone through menopause (meaning no period for at least 12 months). Some older women taking HRT (Hormone Replacement Therapy) for at least two years are also welcome to join. You can't be taking certain medications like weight loss drugs or those for diabetes.

You also can't take part if you are pregnant, breastfeeding, have coeliac disease, diagnosed diabetes, or if you follow a vegetarian or vegan diet. You also need to be able to avoid alcohol for six weeks and be able to speak and understand English.

Could this study suit you?

Answer these quick questions to see if you may be eligible. This is a guide only — the research team makes the final call.

Are you between 18 and 65 years old?
Are you overweight or obese (BMI between 27 and 45)?
Are you generally in good health?
Are you able to avoid alcohol for 6 weeks?
Are you able to speak, read, and understand English?
For older women (55-65), have you gone through menopause (no period for 12 months)?

Answer every question to see your result.

What does participation involve?

If you join, the study will last for 53 days. For the first week, you'll track your normal diet in a food diary at home. After that, all your food and drinks will be provided by the study team, and you'll only eat what they give you. The aim is to make sure your meals meet your energy needs and help with weight loss.

You'll need to visit the Rowett Institute in Aberdeen four times for tests and 17 other times to pick up your food and have your weight checked. These food collections happen on Mondays, Wednesdays, and Fridays, often with a cooked breakfast provided. Throughout the study, you'll have various measurements taken, such as your weight, height, and body composition scans (a bit like a gentle X-ray). Blood and fingerprick samples will also be taken, and you'll wear devices to track your activity and blood sugar. Some participants may also have a small fat sample taken. All these visits happen after you've not eaten or drunk anything since 10 pm the night before.

The diet will start with 3 days of 'maintenance' to keep your weight stable, followed by a 6-week calorie-restricted weight loss diet. Both diets are carefully planned. You'll need to avoid alcohol and only drink decaffeinated drinks provided by the study. The meals are common dishes like pasta and curry.

Potential risks and benefits

Participating in this study comes with potential benefits. Most people can expect to lose weight and body fat, which could improve blood sugar control and overall health. You'll also receive detailed health measurements of your body, metabolism, and hormones that aren't usually available outside of research, along with a summary of your results. The main risks are minor: blood tests might cause brief discomfort or a small bruise, and the fat sample might lead to temporary tenderness. While supervised, the calorie-restricted diet might make you feel a bit hungry or tired, especially at first. You are free to withdraw from the study at any time.

Locations (1)

Some site locations are approximate. We're improving this — please verify with the trial team before travelling.

Human Intervention Studies Unit
City only
Aberdeen, Scotland

Common questions

What is the main goal of this study?

The study aims to understand how age and sex hormones affect weight loss from dieting, to create better, more personalised diet advice for everyone who is overweight or obese.

How long will I need to be involved in the study?

Your total participation in the study will be 53 days.

Will I have to pay for the food provided?

No, all your food and non-alcoholic drinks will be provided by the study team during the main diet phase.

Where does the study take place?

The study is run at the Rowett Institute, University of Aberdeen, in Scotland.

What kind of tests will be done?

Tests include measuring your weight, body fat, energy use, blood samples, and wearing devices to track activity and blood sugar. Some participants may also have a small fat sample taken.

How to find out more

Alexandra Johnstone

alex.johnstone@abdn.ac.uk +44 (0)1224 438614 Official trial record

Always speak to your GP or specialist before deciding to take part in a study.