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
Strong Weight Loss Pills in the UK — What You Need to Know
If you're looking for strong weight loss pills in the UK, prescription medication may be an option. The most effective prescription weight management medications available in the UK are GLP-1 receptor agonists and newer dual-action injections. These are licensed medicines that work alongside diet and exercise to support sustainable weight loss. Unlike over-the-counter supplements, prescription weight loss medication requires a clinical assessment and must be prescribed by a qualified healthcare professional. This guide explains your options, eligibility criteria, and how to access these treatments through the NHS or privately.
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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 Medications
Three main prescription weight management medications are licensed in the UK for eligible adults:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks alongside a reduced-calorie diet and physical activity.
- Wegovy (semaglutide) — A GLP-1 receptor agonist, injected once weekly. In clinical trials, participants achieved average weight loss of approximately 15% of body weight, with individual results varying significantly.
- Saxenda (liraglutide) — A GLP-1 agonist given as a daily injection. This medication supports weight loss through appetite reduction and increased satiety.
All three are prescription-only medicines. Each requires a clinical assessment to confirm eligibility and suitability. These medications work best when combined with dietary changes and increased physical activity — they are not a substitute for lifestyle modifications.
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 and How to Get Started
In the UK, you can access prescription weight loss medication through two routes. NHS access is available through specialist tier 3 or 4 weight management services, typically following referral from your GP. However, NHS availability varies significantly by region and waiting lists can be lengthy. Private access is available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber.
To find out if you're eligible, use our free BMI calculator on this page to check your current BMI. Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, may qualify. Your GP can discuss which route suits you best and help you access treatment through the NHS, or you can pursue private prescribing directly.
- 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 makes a weight loss pill "strong" in the UK?
Prescription weight loss medications like Mounjaro and Wegovy are considered strong because they're clinically proven to support significant weight loss when used with lifestyle changes. Unlike unregulated supplements, they're licensed by the MHRA and prescribed based on individual health assessment. Results vary, but clinical trials show average weight loss of 15–21% of body weight.
Are prescription weight loss pills available on the NHS?
Yes, prescription weight loss medications including Mounjaro and Wegovy are available through NHS specialist weight management services. Access requires referral from your GP to tier 3 or 4 services. Availability varies by region and waiting lists can be long. Private prescribing is also available without NHS referral.
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. Both are injected once weekly. Clinical evidence suggests Mounjaro may support slightly higher average weight loss, but individual results vary significantly. Your prescriber will assess which is more suitable for you.
How quickly do prescription weight loss pills work?
Weight loss with GLP-1 medications typically becomes noticeable within 4–8 weeks, with more significant results visible after 12–16 weeks. The NHS recommends sustainable weight loss of 0.5–1 kg per week. Faster results may be seen with prescription medication, but this varies between individuals.
What happens if prescription weight loss pills aren't suitable for me?
If you're not eligible for prescription medication, your GP can discuss other evidence-based approaches including referral to NHS weight management programmes, dietary support, and structured exercise plans. Our free weight loss calculator and progress tracker can help you set realistic goals and monitor progress with lifestyle changes alone. ```
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.