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
Effective Weight Loss Pills Available in the UK
If you're looking for effective weight loss pills in the UK, prescription medications are available for eligible adults through both NHS and private prescribing routes. Unlike over-the-counter supplements, prescription weight management medicines are clinically proven and regulated by the MHRA. This guide explains the options, how they work, who is eligible, and how to access them. Use our free GLP-1 weight loss calculator to estimate potential results, or check your BMI using our free calculator to understand your starting point for weight management.
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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 prescription weight loss medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are not traditional weight loss pills — Mounjaro and Wegovy are once-weekly injectable medications, while Saxenda is a daily injection.
Mounjaro is a dual GIP and GLP-1 receptor agonist that works by regulating appetite and supporting feelings of fullness. In clinical trials, participants lost an average of 15–21% of their body weight over 72 weeks alongside a reduced-calorie diet and increased physical activity. Wegovy, a GLP-1 agonist, achieved average weight loss of approximately 15% in trials. Both require a prescription following clinical assessment by a licensed prescriber.
These medications support genuine weight management when combined with lifestyle changes, making them distinct from ineffective over-the-counter products often marketed as weight loss pills.
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 Prescribing Routes
In the UK, prescription weight loss medication can be accessed through two main pathways. NHS access involves referral to a specialist tier 3 or tier 4 weight management service through your GP, though waiting times vary significantly by region and availability is limited. Private prescribing offers faster access through GPhC-registered online consultations with UK-licensed prescribers, typically costing £129–£320 monthly depending on dose and provider.
To find out if you're eligible, speak to your GP about your weight management options and goals. Adults with a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea, may be candidates. Your GP or prescriber will assess your individual circumstances and discuss whether prescription weight management is appropriate for you, always alongside lifestyle changes for sustainable results.
- 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 prescription weight loss pills effective in the UK?
Yes. UK-licensed medications like Mounjaro and Wegovy have strong clinical trial evidence showing average weight loss of 15–21%. However, results vary by individual, and these medications work best alongside a reduced-calorie diet and increased physical activity. They're regulated by the MHRA and prescribed only after clinical assessment.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with slightly higher average weight loss outcomes (15–21%) than Wegovy (semaglutide), which is a GLP-1 agonist alone (approximately 15%). Both are once-weekly injections. Individual response varies, and a prescriber will determine which suits you best based on your health profile.
Can I get weight loss medication on the NHS in the UK?
Yes, but NHS access is through specialist weight management services (tier 3/4), not standard GP prescriptions. You'll need a referral from your GP and assessment by a specialist. Availability and waiting times vary significantly by region. Private prescribing offers faster access through online consultations.
How much do prescription weight loss injections cost in the UK privately?
Private costs typically range from £129–£320 per month depending on the medication, dose strength, and provider. Each dose lasts one week. Costs increase as you move to higher doses during the initial adjustment phase. Always check the total cost structure with your chosen provider.
Who is eligible for weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea, cardiovascular disease), may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults may have lower BMI thresholds. A prescriber assesses individual eligibility following consultation.
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.