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
Losing 2 Stone with Prescription Medication in the UK
Losing 2 stone (28 pounds or approximately 12.7 kg) is a significant weight loss milestone achievable through prescription weight management medication available in the UK. For eligible adults, GLP-1 receptor agonist injections like Mounjaro and Wegovy have helped many people reach substantial weight loss alongside lifestyle changes. This guide covers UK-licensed prescription options, eligibility criteria, and how to explore whether medication could support your weight management journey.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Medication
Three prescription-only medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), a dual GIP and GLP-1 receptor agonist; Wegovy (semaglutide), a GLP-1 receptor agonist; and Saxenda (liraglutide), a daily GLP-1 injection. Clinical trials showed that Mounjaro helps participants lose an average of 15–21% of their body weight, whilst Wegovy demonstrated approximately 15% average body weight loss — though individual results vary significantly. Both are once-weekly injections requiring a prescription.
Eligibility for prescription weight loss medication in the UK includes adults with a BMI of 30 kg/m² or above, or a BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator to check your current BMI category. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply due to higher health risks at lower weights.
Losing 2 stone through GLP-1 weight management represents approximately a 10–15% reduction for many adults, which is within the range demonstrated in clinical trials when combined with a reduced-calorie diet and increased physical activity.
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 Getting Started
NHS access: Prescription weight loss medication is available through specialist tier 3 weight management services. You can ask your GP for a referral if you meet eligibility criteria, though NHS availability and waiting times vary significantly by region. Many areas have lengthy waiting lists.
Private access: GLP-1 medications are available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber. This route does not require NHS referral and is often faster, though medications are not funded by the NHS.
Your first step is a conversation with your GP to discuss whether prescription weight loss medication might be appropriate for your health situation. They can assess your BMI, any weight-related health conditions, and whether you have any contraindications. Track your current weight and progress using our free progress tracker to share with your healthcare provider.
Important: Prescription weight loss medications work alongside, not instead of, lifestyle changes. A reduced-calorie diet and increased physical activity remain essential for sustainable weight loss. Losing 2 stone typically takes several months with medication support, and results vary between individuals. Use our GLP-1 weight loss calculator to explore potential results at different doses, though this is an estimate based on clinical trial averages — your actual results depend on your individual circumstances.
- 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.
Is it realistic to lose 2 stone with prescription weight loss medication?
Yes. Clinical trials of Mounjaro and Wegovy showed average weight losses of 15–21% and 15% respectively — which equates to approximately 2 stone for many adults. However, individual results vary significantly depending on your starting weight, dose, adherence, and lifestyle changes. Results are not assured and require combining medication with dietary changes and increased activity.
Can I get Mounjaro or Wegovy on the NHS?
Yes, but access is limited to specialist tier 3 weight management services through NHS referral. Availability and waiting times vary by region — some areas have very long waiting lists. Your GP can refer you if you meet eligibility criteria. Private access through online clinics is often faster but is not funded by the NHS.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, whilst Wegovy (semaglutide) is a GLP-1 receptor agonist only. Both are once-weekly injections. Clinical trials suggest similar average weight loss outcomes, though individual responses vary. Your prescriber will assess which is more suitable based on your health profile.
How long does it take to lose 2 stone with GLP-1 medication?
Weight loss with Mounjaro or Wegovy typically occurs gradually over several months. Clinical trials lasted 68–72 weeks and showed consistent weight loss across this period. Most people require time to reach the maximum dose before weight loss becomes most noticeable. Sustainable weight loss at 0.5–1 kg per week means 2 stone (12.7 kg) would take approximately 3–6 months.
What are the most common side effects of prescription weight loss injections?
Very common side effects include nausea, diarrhoea, vomiting, and constipation — particularly when starting or increasing doses. Most side effects are mild and tend to settle over time. Stomach pain, injection site reactions, and fatigue are also reported. Serious side effects are rare but require immediate medical attention. Always discuss potential side effects with your prescriber.
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.