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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Medical Weight Loss in the UK — Your Complete Guide
Medical weight loss in the UK refers to prescription weight management treatments prescribed by healthcare professionals. These include GLP-1 receptor agonist injections and dual GIP/GLP-1 medications available through both NHS specialist services and private prescribing. Unlike over-the-counter weight loss supplements, medical weight loss is evidence-based, clinically assessed, and prescribed following a full health evaluation. The NHS offers medically-supervised weight management through a structured four-tier pathway, while private options provide faster access without waiting lists. Understanding your options, eligibility, and how these treatments work can help you make an informed decision about your weight management journey.
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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.
How Medical Weight Loss Works in the UK
Medical weight loss in the UK is delivered through two main pathways. The NHS weight management pathway progresses from tier 1 (self-help and digital tools) through to tier 4 (bariatric surgery for severe obesity). Prescription weight loss medications are typically initiated at tier 3, through specialist multidisciplinary weight management services, following referral from your GP. These services assess your eligibility based on your BMI, health conditions, and previous weight loss attempts.
Private medical weight loss operates through GPhC-registered online prescribing services. A qualified UK prescriber conducts an online clinical assessment, and if appropriate, issues a prescription dispensed by a registered pharmacy. Both pathways require you to demonstrate commitment to lifestyle changes—medication is never a substitute for dietary modifications and increased physical activity.
Use our free GLP-1 weight loss calculator to explore potential outcomes with different medications, and check your BMI calculator to understand your starting point for eligibility assessment.
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.
Prescription Weight Loss Medications Available in the UK
Wegovy (semaglutide) is a once-weekly GLP-1 receptor agonist injection licensed for weight management. Clinical trials showed participants lost an average of approximately 15% of their body weight over 68 weeks—though individual results vary significantly. Mounjaro (tirzepatide) is a newer dual GIP/GLP-1 receptor agonist, also once-weekly, with SURMOUNT trial data showing average losses of 15–21% body weight depending on dose.
Saxenda (liraglutide) is a daily GLP-1 injection, available through both NHS and private prescribing. All three are prescription-only medicines requiring clinical assessment before dispensing. Eligibility typically includes BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds due to higher health risks at the same weight.
NHS vs Private Medical Weight Loss — Key DifferencesNHS medical weight loss is free at the point of care but involves GP referral, waiting lists (which can be months or years depending on your region), and access through specialist tier 3 services. Availability varies significantly by integrated care board (ICB). Private medical weight loss offers faster access—typically within days—without NHS referral, but costs £129–£320 per month depending on medication and dose.
Both pathways provide the same licensed medications and require the same clinical assessment standards. Your choice depends on your circumstances: NHS access if you're willing to wait and qualify through your GP; private if you need faster access or prefer to start treatment without referral. Track your weight loss progress with our free progress tracker once you begin treatment.
- 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.
Am I eligible for medical weight loss on the NHS?
NHS medical weight loss eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease). Eligibility is assessed by your GP who can refer you to a tier 3 specialist weight management service. South Asian and other heritage groups may qualify at lower BMI thresholds. Regional availability varies significantly.
How much does private medical weight loss cost in the UK?
Private prescription weight loss medications cost approximately £129–£320 per month depending on the medication and dose. Wegovy and Mounjaro typically cost £180–£320 per month at maximum doses. Initial consultation fees range from £30–£60. Prices vary between private prescribing providers, so it's worth comparing options.
What's the difference between Wegovy and Ozempic?
Both contain semaglutide, but Wegovy is licensed specifically for weight management (up to 2.4 mg weekly), while Ozempic is licensed for type 2 diabetes (up to 2 mg). Using Ozempic for weight loss is off-label and not recommended. Wegovy is the correct prescription weight loss version of semaglutide in the UK.
How quickly will I lose weight with medical weight loss treatment?
The NHS recommends safe weight loss of 0.5–1 kg per week. With prescription GLP-1 medications, clinical trials showed average losses of 15% body weight over 68–72 weeks—but individual results vary significantly. Weight loss typically begins within the first 4–8 weeks. Results depend on your starting weight, dose, diet adherence, and physical activity.
Do I need to keep taking weight loss medication forever?
Medical weight loss medications are typically used for a defined period, usually 1–2 years minimum. Some people maintain their weight loss after stopping; others regain weight. Your prescriber will discuss your individual treatment plan. Sustainable results require permanent lifestyle changes—medication supports this process but doesn't replace diet and exercise changes.
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.