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
Ozempic Weight Loss Injections in the UK
Ozempic (semaglutide) is a prescription-only medication, though the weight loss version licensed in the UK is actually Wegovy. If you're interested in weight loss injections available in the UK, you have several prescription options including Wegovy, Mounjaro, and Saxenda. Understanding which medication might be suitable, how NHS weight loss medication works, and what the eligibility criteria are can help you have an informed conversation with your GP about prescription weight loss options. MyWeightCheck provides free tools including a BMI calculator and GLP-1 weight loss calculator to help you understand your starting point.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Injection Options
In the UK, three prescription medications are licensed specifically for weight management: Wegovy (semaglutide 2.4mg), Mounjaro (tirzepatide), and Saxenda (liraglutide). All are GLP-1 receptor agonists (or in Mounjaro's case, a dual GIP/GLP-1 agonist) that work by reducing appetite and helping you feel fuller after eating. Clinical trial evidence shows that alongside a reduced-calorie diet and increased physical activity, these medications may support weight loss of 10–21% of body weight on average, though individual results vary significantly.
- Wegovy: Once-weekly injection, doses from 0.25mg to 2.4mg over 16 weeks
- Mounjaro: Once-weekly injection, doses from 2.5mg to 15mg, with dual hormone action
- Saxenda: Daily injection, doses from 0.6mg to 3mg
You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions including type 2 diabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds apply if you have South Asian, Chinese, Black African, or Black Caribbean heritage. 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.
NHS vs Private Access in the UK
NHS access is available through specialist tier 3 weight management services, but availability varies significantly by region. Your GP can refer you if you meet criteria, though waiting lists can be lengthy in many areas. Private access is faster: you complete an online consultation with a UK-licensed prescriber, and if approved, the medication is dispensed by a GPhC-registered pharmacy. Costs typically range from £129–£320 per month depending on dose.
To find out if prescription weight loss treatment is right for you, start by calculating your BMI using our free BMI calculator above. Then have a conversation with your GP about whether medication alongside lifestyle changes could support your health goals. Your GP can discuss NHS options, refer you to specialist services if appropriate, or advise you on private options. Weight loss is a marathon, not a sprint—medication works best when combined with sustainable diet and activity changes.
- 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.
Is Ozempic licensed for weight loss in the UK?
Ozempic (semaglutide) is approved for type 2 diabetes in the UK at doses up to 2mg. Wegovy is the licensed UK weight loss version of semaglutide at 2.4mg. Using Ozempic for weight loss is off-label. Your prescriber will recommend the appropriate licensed medication for your needs.
How quickly do weight loss injections work?
Most people begin to notice appetite changes within 1–2 weeks, though significant weight loss typically becomes apparent over 4–8 weeks. Clinical trials showed average weight loss of 10–21% over 68–72 weeks. Results vary considerably between individuals.
Can I get weight loss injections on the NHS?
Yes, through specialist tier 3 weight management services. Your GP can refer you if you meet eligibility criteria (BMI 30+ or 27+ with health conditions). NHS availability varies by region, and waiting lists can be several months to over a year in some areas.
What are the main side effects of GLP-1 weight loss injections?
Very common side effects include nausea, diarrhoea, constipation, and stomach discomfort, particularly during dose increases. Most side effects settle within days or weeks. Serious side effects are rare but can include pancreatitis (severe stomach pain). Your prescriber will discuss risks and benefits in detail.
Do I need to change my diet and exercise if I take a weight loss injection?
Yes. Prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Medication supports appetite control, but sustainable weight loss requires lifestyle changes. Your GP or specialist team will discuss a comprehensive plan with you.
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.