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 Programs in the UK: Prescription Medication Options
If you're looking for weight loss programs in the UK, prescription medications can be part of a comprehensive approach to managing your weight. Alongside diet and exercise, GLP-1 receptor agonist medications and other prescription options are now available through both NHS specialist services and private prescribing routes. This guide explains what's available, who's eligible, and how to access these evidence-based weight management tools. Start by calculating your BMI using our free calculator above to understand where you stand health-wise.
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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 Weight Loss Medications Available Now
Three prescription medications are currently licensed in the UK specifically for weight management:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 receptor agonist administered once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks when combined with lifestyle changes.
- Wegovy (semaglutide 2.4mg) — A GLP-1 receptor agonist given once weekly. The STEP-1 trial demonstrated approximately 14.9% average body weight loss at 68 weeks alongside a reduced-calorie diet and physical activity.
- Saxenda (liraglutide) — A daily GLP-1 injection offering a longer-established option for weight management.
All three are prescription-only and require a clinical assessment. Eligibility typically involves 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. Individual results vary significantly — use our GLP-1 weight loss calculator to explore potential outcomes at different 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.
Accessing Weight Loss Programs: NHS vs Private Routes
NHS access: NICE has approved prescription weight loss medications for use within specialist tier 3 weight management services. You'll need a GP referral and assessment through your local Integrated Care Board (ICB). Availability varies by region, and waiting lists can be lengthy.
Private access: GPhC-registered online prescribing services offer faster access following an online clinical consultation with a UK-licensed prescriber. Costs typically range from £129–£320 monthly depending on the medication and dose. Both routes require the prescriber to confirm you're eligible based on your BMI and health profile.
Next step: Speak with your GP about whether prescription weight loss treatment is appropriate for you. They can assess your individual circumstances and either refer you to NHS services or discuss private options. Calculate your BMI using our free tool to help inform that conversation.
- 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's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 receptor agonist, while Wegovy (semaglutide) works via GLP-1 alone. Both are once-weekly injections. Clinical trials suggest Mounjaro may support slightly higher average weight loss (15–21% vs 14.9%), though individual results vary. Both require prescription and clinical assessment to determine suitability.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition (type 2 diabetes, high blood pressure, heart disease, sleep apnoea, or high cholesterol). For South Asian, Black African, Caribbean, and Chinese adults, lower BMI thresholds apply. Your GP can assess your eligibility and refer you to specialist services if appropriate.
How quickly will I lose weight on these medications?
Clinical trials showed average weight loss of 0.5–1 kg per week, though this varies between individuals. Mounjaro participants lost an average of 15–21% body weight over 72 weeks; Wegovy participants around 14.9% over 68 weeks. Weight loss is achieved alongside a reduced-calorie diet and increased physical activity — the medication isn't a replacement for lifestyle changes.
Can I get weight loss injections privately without NHS waiting lists?
Yes. GPhC-registered online prescribing services offer private access following an online clinical consultation. This typically bypasses NHS waiting lists but requires payment (usually £129–£320 monthly depending on dose and provider). The prescriber must still confirm eligibility based on your BMI and health profile before issuing a prescription.
What if I'm not eligible for prescription medication — are there other UK weight loss programs?
Yes. The NHS offers tier 1 and 2 weight management support including digital tools, community programmes, and behaviour change services. Mediterranean diet, intermittent fasting, and structured low-calorie diets (under medical supervision) are evidence-based options. Your GP can refer you to local weight management services. Use our free BMI calculator and progress tracker to monitor your journey.
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.