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
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Weight Loss Suggestions: Prescription Medication Options in the UK
If you're looking for weight loss suggestions, prescription medication may be an option worth discussing with your GP. The UK has several licensed weight management medicines available, alongside lifestyle changes like diet and exercise. This guide covers the prescription options available in the UK, who may be eligible, and how to access them through NHS or private routes. Use our free BMI calculator above to check where you currently stand, and our GLP-1 weight loss calculator to explore potential outcomes if medication is right 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 Weight Loss Medications: What's Available
Three prescription-only weight management injections are currently licensed in the UK: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are not supplements or cosmetic injections—they are regulated medicines that work by activating hunger-signalling pathways in the brain.
Mounjaro is a dual GIP and GLP-1 receptor agonist, meaning it activates two natural hormone pathways to help regulate appetite and food cravings. In clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
Wegovy is a GLP-1 receptor agonist (single mechanism) available as a once-weekly injection. Clinical evidence shows average weight loss of around 15% of body weight when combined with a reduced-calorie diet and increased physical activity.
Saxenda is also a GLP-1 agonist but requires a daily injection rather than weekly. All three are prescription-only and require a clinical assessment before being prescribed. Your GP or a licensed prescriber will assess your individual eligibility based on your BMI and health status.
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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.
NHS vs Private Access: How to Get Weight Loss Medication
NHS access: Weight loss medication is available through NHS specialist tier 3 and 4 weight management services. You'll typically need a referral from your GP, and availability varies significantly by region and waiting list length. Contact your local Integrated Care Board (ICB) to check what's available in your area.
Private access: Prescription weight loss medication is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route doesn't require an NHS referral and medication can be dispensed more quickly than NHS pathways in many areas.
Whichever route you choose, start by having a conversation with your GP about whether prescription weight management is suitable for you. They can discuss your medical history, current medications, and any health conditions that might affect eligibility. Use our free progress tracker to monitor your weight journey once you've started treatment.
- 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.
Who is eligible for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions (type 2 diabetes, prediabetes, high blood pressure, sleep apnoea, or cardiovascular disease) may be eligible. Lower BMI thresholds apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage due to higher health risks at lower weights. A prescriber will assess your individual eligibility.
What results can I expect from prescription weight loss medication?
Clinical trials show average weight loss of 15–21% of body weight depending on the medication and dose. However, individual results vary significantly. These medications work best alongside a reduced-calorie diet and increased physical activity—they're not a standalone solution. Results depend on your starting weight, adherence, and individual metabolism.
Are weight loss injections safe?
All UK-licensed weight loss medications have undergone rigorous clinical testing and safety monitoring. Side effects are common (nausea, diarrhoea, vomiting) but usually manageable and tend to reduce over time. Serious side effects are rare. Your prescriber will discuss risks and benefits during your assessment and monitor you throughout treatment.
How long do I need to take weight loss medication?
Most people continue treatment for at least 12 months to achieve and maintain weight loss. Some continue longer depending on their progress and health goals. Stopping medication can result in weight regain if lifestyle changes aren't maintained. Your prescriber will help you decide on the right duration for your situation.
Can I get weight loss medication through the NHS quickly?
NHS waiting times vary by region. Some areas have shorter waits, while others may have delays of several months. Private prescribing routes typically offer faster access. Contact your GP or local ICB for current NHS waiting times in your area, and ask about all available options.
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.