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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Extreme Weight Loss Pills: UK Prescription Options
If you're searching for extreme weight loss pills, you may be interested in prescription weight management medications now available in the UK. These are not extreme diet pills but licensed prescription medications that work alongside lifestyle changes. Understanding your options — including eligibility, how they work, and whether NHS weight management support or private prescribing is right for you — is essential before starting any treatment.
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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 Explained
Three prescription weight loss medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro and Wegovy are once-weekly injections, while Saxenda is a daily injection. These are not extreme pills but evidence-based GLP-1 and GIP/GLP-1 receptor agonist medications that may help reduce appetite and support weight loss alongside reduced-calorie diet and increased physical activity.
Clinical evidence: In trials, Mounjaro helped participants lose an average of 15–21% body weight, and Wegovy approximately 15% body weight — though individual results vary significantly. These medications require a prescription from a UK-licensed prescriber following a clinical assessment.
- Mounjaro (tirzepatide): Dual GIP + GLP-1 agonist, doses 2.5 mg to 15 mg once weekly
- Wegovy (semaglutide): GLP-1 agonist, doses 0.25 mg to 2.4 mg once weekly
- Saxenda (liraglutide): GLP-1 agonist, doses 0.6 mg to 3 mg once daily
Eligibility for these medications typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions. All are prescription-only and require assessment by a healthcare professional.
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 Next Steps
In the UK, access to prescription weight loss medication is available through two routes: NHS specialist tier 3/4 weight management services or private prescribing through online clinics. NHS access is typically through specialist services following GP referral, though availability and waiting times vary significantly by region. Private access is available following an online clinical assessment with a UK-licensed prescriber and dispensing by a GPhC-registered pharmacy.
Before considering any weight loss medication, start a conversation with your GP. They can assess your eligibility, discuss whether prescription medication is appropriate for you, and provide information about NHS weight management services in your area. Use our free BMI calculator to check your starting point and our GLP-1 weight loss calculator to understand what results might be realistic if you're prescribed medication. Weight loss is most successful when medication is combined with dietary changes and physical activity.
- 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 extreme weight loss pills safe?
Prescription weight loss medications like Mounjaro and Wegovy are licensed and monitored by the MHRA, meaning they meet UK safety standards. However, they are not suitable for everyone. Side effects are common (nausea, constipation, diarrhoea) but often improve with time. Always discuss safety with your GP or prescriber based on your individual health.
How much weight can you lose with prescription medication?
Clinical trials show Mounjaro helps average weight loss of 15–21% body weight and Wegovy approximately 15%, alongside diet and exercise. However, individual results vary significantly. Some people lose more, some less. Your prescriber will discuss realistic expectations for you specifically.
Can I get extreme weight loss pills on the NHS in the UK?
Yes, prescription weight loss medications are available through NHS specialist tier 3 weight management services if you're eligible (BMI 30+, or 27+ with health conditions). Access is through GP referral to specialist services. Availability varies by region and waiting times can be lengthy.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP + GLP-1 agonist with potentially stronger appetite suppression, whilst Wegovy (semaglutide) is a single GLP-1 agonist. Both are once-weekly injections with similar average weight loss results in trials. Your prescriber will advise which is more suitable for you.
Do I need to diet and exercise if I take weight loss medication?
Yes. Prescription weight loss medications work best alongside a reduced-calorie diet and increased physical activity. They are not a replacement for lifestyle changes. Most people who successfully lose weight and keep it off combine medication with sustainable dietary and exercise habits.
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.