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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Top Weight Loss Shakes and UK Prescription Options
Weight loss shakes can be a convenient part of a reduced-calorie diet, but prescription weight management medication is now available in the UK for eligible adults. If you're looking for structured support to lose weight, you have several options — from meal replacement shakes to licensed prescription injections like Mounjaro and Wegovy. This guide covers both approaches and helps you understand which route might suit your needs, alongside practical next steps for discussing weight management with your GP.
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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 Prescription Weight Loss Options
For adults struggling with weight management, the NHS and private prescribers now offer three prescription-only medications specifically licensed for weight loss in the UK:
- Mounjaro (tirzepatide) — a once-weekly injection that works on two hormone pathways, helping reduce appetite and support feeling fuller. In clinical trials, users lost an average of 15–21% of their body weight alongside a reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection licensed for weight management. Clinical trials showed average weight loss of around 15% over 68 weeks.
- Saxenda (liraglutide) — a daily GLP-1 injection, also available through NHS specialist services and private prescribing.
These are prescription-only medicines that require a clinical assessment before being prescribed. They are typically used alongside dietary changes and increased physical activity, not as a substitute for lifestyle modifications. Individual results vary significantly.
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 Access vs Private Prescription Routes
In the UK, prescription weight loss medication is available through two routes. The NHS route requires referral to a specialist tier 3 or 4 weight management service, usually via your GP. NHS access is free but waiting lists vary significantly by region — some areas have months-long queues. The private route involves an online consultation with a UK-licensed prescriber followed by dispensing through a registered pharmacy, typically costing £150–£300 per month depending on dose. Eligibility criteria are similar: adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Your GP can discuss which route is most appropriate for your circumstances.
- 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.
Are weight loss shakes or prescription injections more effective?
Clinical evidence shows prescription GLP-1 and GIP/GLP-1 medications produce greater average weight loss (15–21%) than meal replacement shakes alone. However, weight loss shakes can support a calorie deficit when used as part of a structured diet plan. Prescription medications work by appetite suppression, while shakes work through calorie reduction. The most effective approach for you depends on your circumstances, health conditions, and personal preference — discuss with your GP.
How do I know if I'm eligible for Mounjaro or Wegovy in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition (diabetes, high blood pressure, sleep apnoea, or cardiovascular disease). If you're of South Asian, Chinese, Black African, or Black Caribbean descent, lower thresholds may apply. Your GP or a licensed private prescriber will assess your individual eligibility based on your health history, current medications, and medical circumstances.
Can I get weight loss injections on the NHS?
Yes, Mounjaro, Wegovy, and Saxenda are available through NHS specialist weight management services. Access varies by region — you'll need a GP referral to your local tier 3 or 4 specialist service. Waiting times can be considerable in many areas. Private prescribing offers faster access but involves costs. Ask your GP about availability and waiting times in your area.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical data suggests Mounjaro may produce slightly greater average weight loss (up to 21% vs 15%), but both are effective. Mounjaro is dosed at 2.5–15 mg weekly; Wegovy goes up to 2.4 mg weekly. Both require a prescription and clinical assessment. Individual results vary considerably.
Do I need to follow a diet and exercise plan while using weight loss medication?
Yes. Prescription weight loss injections work most effectively alongside a reduced-calorie diet and increased physical activity. These medications support appetite reduction but are not designed to work alone. The NHS and your prescriber will provide guidance on dietary and lifestyle changes to maximise results and maintain weight loss long-term. Try our free GLP-1 weight loss calculator above to explore potential outcomes with different approaches.
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.