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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Losing 1 Stone with Weight Loss Medication in the UK
Losing 1 stone (6.35 kg or 14 lbs) is a significant health milestone that many UK adults aim for. If you're considering prescription weight loss medication to help achieve this, several evidence-based options are available through both the NHS and private prescribing. These medications work alongside diet and physical activity changes, not instead of them. Understanding what's available, how they work, and whether you're eligible is the first step toward making an informed decision about your health.
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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 for 1 Stone Goals
Three main prescription options are licensed in the UK for weight management:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist. Clinical trials showed participants lost an average of 15–21% of their body weight. At a starting dose of 2.5 mg weekly, increasing to a maximum of 15 mg weekly.
- Wegovy (semaglutide) — A GLP-1 receptor agonist available as a once-weekly injection. Clinical trials demonstrated average weight loss of around 15% of body weight on the maximum dose of 2.4 mg weekly.
- Saxenda (liraglutide) — A GLP-1 medication given as a daily injection, maximum dose 3 mg daily. Less commonly prescribed than Mounjaro and Wegovy but still available.
All three require a prescription and a clinical assessment. Individual results vary significantly — losing 1 stone equates to approximately 14% of body weight for an 80 kg adult, which sits within typical weight loss ranges seen in clinical trials.
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 in the UK
NHS route: Weight loss medications are available through specialist tier 3 weight management services, but access is limited and varies by region. Your GP can refer you, but waiting lists can be lengthy in many areas.
Private route: GPhC-registered online services offer assessment and prescription if you meet eligibility criteria (BMI 27+ with health conditions, or BMI 30+). This is often faster than NHS routes.
Both routes require clinical assessment to confirm suitability. Your prescriber will review your medical history, current medications, and weight management goals. Losing 1 stone is a realistic goal for many eligible adults, though this depends on your starting weight, dose, and lifestyle changes you make alongside medication.
- 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.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight depending on the medication and dose. Individual results vary significantly. Losing 1 stone would represent approximately 14% of body weight for an 80 kg adult. Weight loss also depends on diet, physical activity, and how your body responds to the medication.
Am I eligible for weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. Eligibility is assessed individually by your GP or a specialist service. South Asian, Black African, and Black Caribbean adults may have lower BMI thresholds.
How long does it take to lose 1 stone with these medications?
At a typical loss rate of 0.5–1 kg per week (combined with dietary changes), losing 1 stone (6.35 kg) would take approximately 6–12 weeks. However, this varies depending on the medication dose you're on and your individual response. Dose increases typically happen every 4 weeks.
Can I use MyWeightCheck tools to track my progress if I start medication?
Yes — use our free progress tracker to log your weight loss journey week by week. Our BMI calculator helps you see how your BMI changes as you lose weight, and our weight converter lets you easily switch between stone, pounds, and kilograms as you track your 1 stone goal.
What happens after I've lost 1 stone — do I stay on the medication?
This depends on your prescriber's guidance. Some people continue medication to prevent weight regain, while others may step down. Sustainable weight loss requires ongoing lifestyle changes — diet and physical activity — whether you continue medication or not. Your prescriber will discuss the best approach for you.
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.