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
GLP-1 Reviews for Weight Loss in the UK
GLP-1 medications have become increasingly talked about in weight management conversations across the UK. These prescription injections work by mimicking natural gut hormones that help regulate appetite and support feeling fuller after meals. If you're considering weight loss medication or curious about what people report, understanding how GLP-1 drugs work, what clinical evidence shows, and how to access them in the UK is essential. Our GLP-1 weight loss calculator can help you explore potential outcomes at different doses, and this guide covers everything you need to know about these medications and whether they might be suitable for you.
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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 GLP-1 Medications and Clinical Evidence
Three GLP-1 receptor agonist medications are currently licensed in the UK for weight management: Wegovy (semaglutide), Mounjaro (tirzepatide), and Saxenda (liraglutide). Mounjaro is technically a dual GIP and GLP-1 agonist, which activates two hormone pathways. Clinical trials show these medications help participants lose significant weight when used alongside reduced-calorie diets and increased physical activity.
In the SURMOUNT-1 trial, participants on Mounjaro 15mg lost an average of around 20.9% of their body weight over 72 weeks. Wegovy users in STEP-1 trials lost approximately 14.9% at the maximum dose. Saxenda, taken daily rather than weekly, showed average weight loss of around 5.2 kg (11.5 lbs) in clinical trials. Individual results vary considerably, and these medications are prescription-only, meaning they require clinical assessment before being prescribed.
To check your current weight status and calculate a healthy weight range, try our free BMI calculator above — it also shows where your weight falls according to NHS guidelines.
Clinically BackedWeight Loss
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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 GLP-1 Medication: NHS vs Private
In the UK, GLP-1 medications for weight management are available through two routes: NHS specialist services and private prescribing. NHS access requires referral to a tier 3 or 4 specialist weight management service, usually through your GP. However, NHS availability varies significantly by region and waiting times can be lengthy in many areas.
Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. To explore whether you're eligible, start by speaking with your GP about weight loss options in your area. Your GP can assess your BMI, any weight-related health conditions (such as type 2 diabetes, high blood pressure, or sleep apnoea), and discuss whether prescription medication might be appropriate for you. A clinical assessment is always required before medication is prescribed, regardless of whether you choose NHS or private routes.
- 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 do real reviews say about GLP-1 medications for weight loss?
Clinical trials show consistent weight loss across GLP-1 medications, though individual experiences vary. Common feedback includes appetite reduction, feeling fuller after smaller meals, and gradual weight loss over weeks and months. Side effects like nausea are reported by many users initially but often improve as the body adjusts. Real-world experiences depend on dose, lifestyle changes, and individual physiology.
Are GLP-1 medications available on the NHS in the UK?
Yes, GLP-1 medications (Mounjaro, Wegovy, and Saxenda) are available on the NHS through specialist tier 3 and tier 4 weight management services. Access requires a GP referral and varies by region and ICB. Private access is also available without NHS referral through online prescribers, though this involves private cost. Check with your local NHS weight management service for current availability.
How do I know if I'm eligible for GLP-1 medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with at least one weight-related health condition (type 2 diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). Lower thresholds apply for South Asian, Chinese, Black African, and Caribbean adults. Your GP or a clinical prescriber will assess your individual eligibility following a consultation.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist and typically shows slightly higher average weight loss (around 20.9%) than Wegovy (semaglutide), which is a GLP-1 agonist only (around 14.9%). Both are once-weekly injections. Mounjaro starts at 2.5mg and goes up to 15mg; Wegovy starts at 0.25mg and reaches 2.4mg. Individual results vary, and the best choice depends on your clinical assessment.
Can I use our weight loss calculator to estimate outcomes with GLP-1 medication?
Yes—our GLP-1 weight loss calculator above is designed to help you explore potential weight loss at different doses based on clinical trial data. It shows projected weight loss in kg and stone using UK measurements. Remember these are estimates: actual results depend on your starting weight, dose, lifestyle changes, and individual factors. Use it alongside your GP consultation to understand possibilities.
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.