GLP-1 clinical trials test weight-loss medications such as semaglutide (Wegovy) and tirzepatide (Mounjaro), and offer a route to access these treatments under medical supervision, often free and sometimes paid. With NHS access tightly restricted and private prescriptions costly, clinical trials are a legitimate way for eligible people to try investigational GLP-1 treatments. This guide explains how they work, who can take part, and how to find a genuine study.
What is a GLP-1 weight-loss trial?
A GLP-1 clinical trial is a research study testing a glucagon-like peptide-1 (GLP-1) receptor agonist — a class of drug that reduces appetite and supports weight loss. Well-known GLP-1 medications include semaglutide (sold as Wegovy) and the dual GLP-1/GIP drug tirzepatide (sold as Mounjaro). Trials test new GLP-1 drugs, new doses, oral versions, or how existing ones perform in different groups of people.
Demand is enormous: an estimated 3.3 million UK adults are expected to use weight-loss injections in 2026. Because NHS access is limited and private treatment is expensive, a growing number of people look to clinical research as a way to access these medications safely.
Why consider a clinical trial for weight-loss medication?
NHS access to drugs like Mounjaro and Wegovy is restricted. The NHS England tirzepatide rollout began in June 2025 and, in its first phase, is limited to adults with a BMI of 40 or above who also have several weight-related health conditions. Wegovy is available through Tier 3 specialist weight-management services under similar restrictions. Many people who want these treatments do not meet the NHS criteria, and private prescriptions can cost a significant amount each month.
A clinical trial can offer:
- Access to investigational GLP-1 treatments under close medical supervision
- Regular health checks and monitoring at no cost
- In some studies, compensation for your time and travel
- A way to contribute to research on obesity treatment
It’s important to understand that trials are research, not treatment on demand: some participants receive a placebo, and the goal is to study the medicine rather than guarantee a result.
Who can take part in a GLP-1 trial?
Eligibility depends on the specific study. Common criteria include:
- A BMI above a set threshold (often 30+, or sometimes 27+ with a weight-related condition)
- Being within a certain age range, usually 18 and over
- Having, or not having, conditions such as type 2 diabetes or high blood pressure
- Not currently taking another weight-loss medication
- General health and other medical history
Some studies recruit people living with obesity, while early-phase studies may recruit healthy volunteers within a specific BMI band. Each trial sets out its full inclusion and exclusion criteria in the participant information sheet.
Do GLP-1 weight-loss trials pay?
It varies. Patient-focused trials run by the NHS or universities often provide the medication and monitoring free but cover travel expenses only. Early-phase studies run by private clinical research units may pay for time and inconvenience, ranging from a few hundred pounds up to £3,000 or more for studies with residential stays. For a full breakdown, see our guide to the best-paid clinical trials.
How to find a GLP-1 or weight-loss drug trial
- Search a registered source. Use the UK’s Be Part of Research service or the WHO registry to find obesity and GLP-1 studies near you.
- Check the study is registered and approved. Every UK medicine trial must be authorised by the MHRA and an independent ethics committee, as the NHS explains.
- Complete the eligibility screening. You’ll answer questions about your BMI, health and medication history.
- Read the participant information sheet fully — including whether the study involves a placebo, any compensation, and your right to withdraw.
- Never pay to take part. A genuine trial never charges you a fee, and never sells you medication directly.
A safety warning about online sellers
The popularity of Wegovy and Mounjaro has led to a surge in unregulated online sellers offering cheap weight-loss drugs. These are not clinical trials, and the medication may be unsafe or counterfeit. A legitimate clinical trial is run by a regulated research organisation, is MHRA-approved, never asks you to pay, and provides medical supervision throughout. If something is sold to you as a “trial” but asks for payment, it is not a genuine clinical trial.
Are GLP-1 trials safe?
UK GLP-1 trials operate under strict safeguards: every study is authorised by the MHRA and approved by an independent research ethics committee, with medical supervision throughout. GLP-1 medications commonly cause gastrointestinal side effects such as nausea, which the study team will monitor. You can withdraw at any time, without giving a reason. Our guide to clinical trial safety and compensation covers the protections in more depth.
Related guides
For a broader view, see our guides to weight-loss clinical trials near you and diabetes clinical trials, since many GLP-1 studies also recruit people with type 2 diabetes.
The bottom line
GLP-1 clinical trials offer a legitimate, supervised route to access weight-loss medications like semaglutide and tirzepatide, particularly for people who don’t meet NHS criteria. Use a registered source, confirm the study is MHRA-approved, never pay to take part, avoid unregulated online sellers, and read the information sheet before you consent.
Frequently Asked Questions
Can I get Mounjaro or Wegovy through a clinical trial?
Sometimes. Some trials test these specific drugs or similar GLP-1 medications. Bear in mind that in many studies some participants receive a placebo, and eligibility criteria apply.
Do GLP-1 weight-loss trials pay?
Some do. Patient studies often provide the medication free but cover expenses only, while early-phase studies may pay several hundred to a few thousand pounds.
What BMI do I need for a GLP-1 trial?
It varies by study. Many obesity trials require a BMI of 30 or above, while some accept a BMI of 27 or above with a weight-related condition. The criteria will state the requirement.
Is it safe to join a GLP-1 trial?
Yes, when it’s a genuine MHRA-authorised, ethics-approved study with medical supervision. Avoid anything that asks you to pay or sells medication directly — that is not a clinical trial.
How do I find a GLP-1 trial near me?
Use the NHS Be Part of Research service, search the WHO registry, or compare studies through CheckMyTrial.
Find weight-loss and GLP-1 trials near you
CheckMyTrial helps you compare clinical trials across the UK by location, condition and study type. Browse current trials or read how clinical trials work before you apply.