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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5 Stone Weight Loss: Prescription Medication Options in the UK
Losing 5 stone (approximately 32 kg) is a significant health goal that many UK adults aim for. If you're looking at weight loss medication to support this journey, the NHS and private prescribers now offer several prescription-only options proven to help with weight management. Understanding which medications are available, who is eligible, and how to access them through the NHS or private route is the first step towards achieving sustainable weight loss alongside lifestyle changes.
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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 medications are currently licensed in the UK for weight management:
- Mounjaro (tirzepatide) — A once-weekly injection that activates both GIP and GLP-1 hormones. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks when combined with diet and exercise changes.
- Wegovy (semaglutide 2.4 mg) — A once-weekly GLP-1 injection. In clinical trials, participants achieved approximately 15% average body weight loss at the maximum dose.
- Saxenda (liraglutide) — A daily GLP-1 injection, available for several years in the UK. Results vary, with average weight loss around 5–10% of body weight.
All three are prescription-only medicines requiring a clinical assessment before being prescribed. Individual results vary significantly based on lifestyle, genetics, and adherence to a reduced-calorie diet and increased physical activity. Use our free GLP-1 weight loss calculator to explore projected weight loss at different medication doses.
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.
Eligibility and How to Access Treatment
You may be eligible for prescription weight loss medication if your BMI is 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds apply if you are of South Asian, Chinese, Black African, or Black Caribbean heritage.
On the NHS: Referral to a specialist tier 3 weight management service is typically required. Availability varies significantly by region, and waiting times can extend from several months to over a year in some areas.
Privately: Licensed prescribers offer online consultations and prescriptions through GPhC-registered pharmacies, usually without an NHS referral. Costs typically range from £129–£320 monthly depending on medication and dose. Start by checking your BMI using our free BMI calculator to understand your baseline.
- 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 5 stone using prescription weight loss medication?
Weight loss medication may support a 5-stone loss goal when combined with a reduced-calorie diet and increased physical activity. Clinical trials show an average loss of 15–21% body weight over 72 weeks with some medications. However, results vary individually. Your GP or prescriber can assess whether medication is appropriate for your circumstances and help set realistic targets.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) activates both GIP and GLP-1 hormones and showed slightly higher average weight loss (15–21%) in trials compared to Wegovy (semaglutide), which is a single GLP-1 agonist with approximately 15% average loss. Both are once-weekly injections. The choice depends on individual health factors assessed by your prescriber.
How long does it take to lose 5 stone on weight loss medication?
Based on clinical trial data, reaching 5 stone loss typically takes 12–18 months at a safe rate of 0.5–1 kg per week. Some people may lose weight faster with medication support, but very rapid loss increases muscle loss risk. Your prescriber will discuss realistic timelines based on your starting weight and chosen medication.
Do I need a referral from my GP to access weight loss medication?
On the NHS, a GP referral to specialist weight management services is usually required. Access varies by region and availability. Privately, you can access licensed prescribers without an NHS referral through online consultations. Either route requires a clinical assessment to confirm the medication is safe and appropriate for you.
What happens after I reach my weight loss goal?
Weight loss medications are typically continued long-term because weight regain often occurs if treatment stops. Your prescriber will discuss maintenance strategies, including whether to continue medication, adjust doses, or transition to lifestyle management alone. Your GP can monitor your progress using our free progress tracker to log weight changes over time. ```
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.