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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Semaglutide in the UK — NHS Prescribing & Access Guide
Semaglutide is a prescription-only GLP-1 receptor agonist licensed in the UK for weight management in adults. Known by the brand name Wegovy, semaglutide has been approved by the MHRA and recommended by NICE for eligible adults. Access in the UK is available through both NHS specialist weight management services and private online prescribing following clinical assessment. Understanding the evidence, eligibility criteria, and both access routes can help you make an informed decision about whether this weight loss injection is right for you.
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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.
NHS Eligibility & NICE Guidance for Semaglutide
NICE approved semaglutide for NHS weight management services in 2021, and it remains the recommended first-line injectable treatment for eligible adults in England, Scotland, Wales, and Northern Ireland.
You may be eligible for NHS semaglutide if:
- Your BMI is 30 kg/m² or above, OR your BMI is 27–29.9 kg/m² with at least one weight-related health condition (type 2 diabetes, prediabetes, high blood pressure, abnormal cholesterol, sleep apnoea, or cardiovascular disease)
- For South Asian, Chinese, Black African, or Black Caribbean adults, lower thresholds apply — eligibility may begin at BMI 27.5 or above
- You have already tried lifestyle changes (diet and exercise) without sufficient results
NHS access is through tier 3 specialist weight management services, typically reached via GP referral. Availability and waiting times vary significantly by region (integrated care board). In many areas, NHS waiting lists are substantial, ranging from several months to over a year.
The clinical evidence supporting semaglutide comes from the STEP trials, where at the maximum dose of 2.4 mg once weekly, participants lost an average of approximately 14.9% of their body weight over 68 weeks alongside a reduced-calorie diet and increased physical activity — though individual results vary considerably.
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 for Semaglutide in the UK
NHS route: Free at point of use once prescribed, but access is limited to tier 3 specialist services via GP referral. Waiting lists can be very long in many regions. Once on treatment, NHS prescriptions are dispensed by NHS hospital pharmacy or community pharmacy.
Private route: Available through GPhC-registered online pharmacies following an online clinical consultation with a UK-licensed prescriber. No NHS referral required, faster access (typically within 1–2 weeks), but costs approximately £129–£250 per month depending on dose. Many private providers now offer semaglutide specifically marketed as Wegovy or generic semaglutide for weight management.
Both routes require a clinical assessment to confirm eligibility and suitability. Use our free weight converter and BMI calculator to understand your starting point, and try our GLP-1 weight loss calculator to project potential outcomes at different doses.
- 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 semaglutide (Wegovy) available on the NHS in the UK?
Yes, semaglutide is available on the NHS through NICE-approved tier 3 specialist weight management services. Access is by GP referral, and availability varies by region. Many areas have long waiting lists (several months to over a year). Private prescription is an alternative with faster access but a cost.
What dose of semaglutide is used for weight management in the UK?
Wegovy uses semaglutide at doses from 0.25 mg up to a maximum of 2.4 mg once weekly. Dosing is gradual over approximately 16 weeks. The 2.4 mg maintenance dose is the standard therapeutic dose for weight management. Do not confuse this with Ozempic (type 2 diabetes formulation, max 2 mg).
Who is eligible for semaglutide on the NHS?
Adults with a BMI of 30 or above, or 27–29.9 with a weight-related health condition, may be eligible. South Asian, Chinese, Black African, and Black Caribbean adults have lower thresholds (27.5+). You must have tried lifestyle changes first. Your GP can assess your individual suitability.
What weight loss can I expect from semaglutide based on UK clinical evidence?
The STEP-1 trial showed average weight loss of approximately 14.9% body weight at 2.4 mg over 68 weeks, alongside reduced-calorie diet and exercise. Individual results vary significantly. Some lose more, some less. Results depend on adherence, diet, exercise, and individual metabolism.
How do I access semaglutide privately in the UK if I don't want to wait for NHS?
Private online consultations with UK-licensed prescribers can assess your eligibility and issue a prescription. GPhC-registered pharmacies then dispense Wegovy or semaglutide. Cost is typically £129–£250 monthly depending on dose. Always check the provider is registered with the GPhC and employs UK-licensed prescribers.
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.