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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Two Stone Weight Loss: UK Prescription Weight Management Options
Losing two stone (12.7 kg) is a significant health goal that many UK adults pursue through various methods. For eligible adults, prescription weight management medications are now available through the NHS and private prescribing services. These medications are designed to work alongside dietary changes and increased physical activity to support sustainable weight loss. Understanding what's available, who qualifies, and how these treatments work can help you make an informed decision about your weight management journey. This guide covers the prescription options available in the UK and how to explore whether they're suitable for you.
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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 medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). All three work by activating natural hormone pathways that regulate appetite and help you feel fuller after smaller meals.
Mounjaro is a once-weekly injection using a dual GIP and GLP-1 mechanism. Clinical trials showed participants lost an average of 15–21% of their body weight—for someone at two stone above a healthy weight, this could represent significant loss. Wegovy is also once-weekly, using GLP-1 alone, with average losses around 15% in trials. Saxenda is a daily injection offering similar benefits.
Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Your GP or a licensed prescriber will assess whether you're suitable following a clinical consultation. Individual results vary significantly—weight loss depends on your starting point, lifestyle changes, and how your body responds to the medication.
Clinically BackedWeight Loss
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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 in the UK
NHS access to prescription weight loss medication is through specialist tier 3 weight management services, typically requiring a GP referral. Availability and waiting times vary considerably by region—some areas have long waiting lists. Private prescribing is available through GPhC-registered online services; you complete an online assessment and a UK-licensed prescriber decides if treatment is appropriate. Private options are accessible without NHS referral but do require payment, typically ranging from £129–£320 monthly depending on dose.
Whichever route you choose, weight loss medications work best alongside a reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator to explore potential outcomes at different doses, and our BMI calculator to understand your current health baseline. Speaking with your GP is always a good starting point—they can discuss options, check for any contraindications, and advise on the best pathway for you.
- 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.
Can I lose two stone with prescription weight loss medication?
Clinical trials show average weight losses of 15–21% with Mounjaro and around 15% with Wegovy. Two stone represents a significant amount, and whether you achieve this depends on your starting weight, the dose prescribed, your diet and activity levels, and individual factors. Results vary considerably between individuals—your GP or prescriber can give you a more personalised estimate.
Am I eligible for prescription weight loss medication on the NHS?
NHS eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions. You'd need a GP referral to a specialist tier 3 weight management service. Eligibility criteria and waiting times vary by region. Contact your GP surgery to find out what's available in your area.
How long does it take to lose two stone with these medications?
Weight loss is gradual and sustainable. The NHS recommends aiming for 0.5–1 kg per week, meaning two stone would typically take 3–6 months minimum with consistent effort. Prescription medications can support this, but they work best alongside dietary changes and increased physical activity.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections. Mounjaro uses a dual GIP and GLP-1 mechanism and showed slightly higher average weight loss (15–21%) in trials compared to Wegovy's GLP-1 alone mechanism (around 15%). Both require prescription and clinical assessment. Your prescriber will advise which suits you best.
Do I have to pay for prescription weight loss medication in the UK?
On the NHS, if you're eligible and referred to a specialist service, there's no medication cost—but waiting lists exist in most areas. Private prescribing requires payment (typically £129–£320 monthly). Both routes require a valid prescription from a UK-licensed prescriber following clinical assessment.
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.