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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Weight Loss Rewards: What UK Prescription Medication Can Achieve
Weight loss rewards go beyond the number on the scales — they include improved health, increased energy, and better quality of life. If you're considering weight management in the UK, prescription medications like Mounjaro and Wegovy may help eligible adults achieve sustainable results. Understanding what these treatments can realistically offer, alongside lifestyle changes, is the first step towards meaningful health improvements. This guide explores the evidence, eligibility criteria, and how to access prescription weight loss options through the NHS or privately.
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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 Options
Three prescription medications are currently licensed in the UK for weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, administered as a once-weekly injection with doses ranging from 2.5 mg to 15 mg. Clinical trials showed it helped participants lose an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly. Wegovy (semaglutide) is a GLP-1 agonist, also injected once weekly, reaching a maximum dose of 2.4 mg. In clinical trials, Wegovy supported average weight loss of approximately 15% of body weight alongside reduced-calorie diet and increased physical activity. Saxenda (liraglutide) is a daily GLP-1 injection with a maximum dose of 3 mg daily.
Eligibility for prescription weight loss medication in the UK typically includes adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. People of South Asian, Chinese, Black African, or Black Caribbean heritage may be eligible at lower BMI thresholds due to higher metabolic health risks at the same BMI. All prescription weight loss medications require a clinical assessment before being dispensed — they are not suitable for everyone.
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 Next Steps
NHS Access: Prescription weight loss treatment is available through NHS specialist tier 3 weight management services following a GP referral. However, availability varies significantly across regions, and waiting lists can be substantial in many areas. Your GP can discuss whether referral is appropriate and what services are available locally.
Private Access: UK-licensed prescribers also offer weight loss medication consultations online, with prescription dispensing through GPhC-registered pharmacies. This route does not require NHS referral and is typically faster, though there is a private cost.
Start by speaking with your GP about weight management options. They can assess your individual health circumstances, discuss whether prescription medication is suitable, and guide you towards NHS or private pathways. Use our free BMI calculator to understand your current weight category, and our GLP-1 weight loss calculator to explore potential outcomes at different medication doses — these tools can help frame the conversation with your healthcare provider.
- 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.
What are the real weight loss rewards of prescription medication?
Clinical evidence shows prescription GLP-1 medications may help participants lose 15–21% of body weight alongside lifestyle changes. Individual results vary significantly. More importantly, even modest weight loss (5–10%) can reduce blood pressure, improve blood sugar control, lower cholesterol, ease joint pain, and reduce disease risk — these are the meaningful health rewards beyond the scales.
How long does it take to see weight loss rewards from Mounjaro or Wegovy?
Most people notice appetite changes within the first few weeks. Measurable weight loss typically becomes evident within 4–8 weeks, with the majority of weight loss occurring between weeks 8–20. These medications work best alongside reduced-calorie diet and increased physical activity — results vary between individuals.
What is the difference between NHS and private weight loss medication in the UK?
Both routes use the same UK-licensed prescription medications. NHS access is through specialist weight management services (longer waitlists, no private cost) following GP referral. Private access is through online prescribers and GPhC-registered pharmacies (faster, private cost). The medication quality and clinical suitability assessment are equivalent.
Am I eligible for prescription weight loss medication on the NHS?
Generally, you may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes, high blood pressure, or cardiovascular disease. Lower BMI thresholds apply for South Asian, Chinese, Black African, or Black Caribbean adults. Your GP can assess your individual eligibility and discuss options.
Can I use our BMI calculator to check if I might be eligible for weight loss medication?
Yes. Use our free BMI calculator on this page to find your current BMI and see which NHS category you fall into. This gives you a baseline before speaking with your GP. If your BMI suggests you may be eligible, use our weight loss calculator to explore projected results at different medication doses — this information can help you have an informed conversation with your healthcare provider.
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.