The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
Weight Loss Group Options in the UK
A weight loss group can provide valuable support, accountability, and community during your weight management journey. In the UK, you have multiple options: community support groups, NHS-backed programmes, and prescription weight loss medications. Many people find the most effective approach combines group support with medical guidance. This guide covers UK prescription weight loss options, how to access them, and what the evidence shows about their effectiveness.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
UK-Licensed Weight Loss Medications
If you're looking for prescription weight loss support in the UK, three main medications are currently licensed for weight management:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed an average weight loss of 15–21% of body weight at 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — A GLP-1 receptor agonist, also injected once weekly. Evidence from the STEP trials demonstrated average weight loss of around 15% of body weight.
- Saxenda (liraglutide) — A daily GLP-1 injection, offering an alternative to weekly injections.
All three are prescription-only medicines that require a clinical assessment. Eligibility typically includes a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Accessing Weight Loss Support: NHS vs Private Routes
In the UK, weight loss medication access varies by route. The NHS provides prescription weight loss treatment through specialist tier 3 weight management services, typically following GP referral. However, NHS availability varies significantly by region and waiting lists can be substantial in many areas.
Private access is available through GPhC-registered online prescribers following a clinical assessment. This route does not require NHS referral.
Whichever path you choose, sustainable weight management combines medication with lifestyle changes — reduced-calorie diet and increased physical activity. Your GP can discuss which option is most suitable for you and whether prescription weight loss medication is appropriate for your individual circumstances. Track your progress with our free progress tracker once you begin your weight loss journey.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
What is a weight loss group and how does it help?
A weight loss group provides community support, shared experiences, and accountability. Members discuss challenges, share strategies, and celebrate progress together. Groups can be NHS-run, community-based, or online. Many people find peer support motivates sustained behaviour change and makes the weight loss journey less isolating.
Am I eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may be eligible at lower BMI thresholds. A GP or prescriber will assess your individual eligibility after clinical evaluation.
How much weight can I expect to lose with GLP-1 medication?
Clinical trials show average weight loss of 15–21% of body weight depending on the medication and dose. However, individual results vary considerably — some people lose more, others less. Weight loss medication works best alongside a reduced-calorie diet and increased physical activity. Results are not assured, and your GP can discuss realistic expectations for you.
What's the difference between NHS and private weight loss treatment?
NHS treatment is available through specialist weight management services (typically tier 3) following GP referral, though availability and waiting times vary by region. Private treatment is accessed through online prescribers without NHS referral. Both routes require clinical assessment. Cost is covered by the NHS on one route and paid privately on the other.
Do weight loss medications have side effects?
Yes. GLP-1 medications commonly cause nausea, diarrhoea, constipation, and stomach discomfort, especially early on. Side effects often improve over time. Serious side effects are rare but can include pancreatitis or gallbladder problems. Your prescriber will discuss potential side effects and monitor you during treatment. Report any concerns to your GP immediately.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.