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
How Effective Is Wegovy for Weight Loss in the UK?
Wegovy (semaglutide) is a GLP-1 receptor agonist injection licensed in the UK for weight management in adults. Clinical trials showed an average weight loss of around 15% of body weight over 68 weeks — though individual results vary significantly. Effectiveness depends on factors including dose, lifestyle changes, and personal metabolism. This guide explains how effective Wegovy actually is, what it costs in the UK, and how to access it through both private and NHS routes.
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.
Wegovy Effectiveness and Cost in the UK Private Market
In clinical trials (STEP-1), adults taking Wegovy 2.4 mg — the maximum maintenance dose — lost an average of approximately 14.9% of their body weight alongside reduced-calorie diet and increased physical activity. Results ranged from modest weight loss to 22% or more, demonstrating that individual effectiveness varies considerably. On lower doses (0.5 mg to 1.7 mg), average weight loss was lower, typically 8–12% of body weight.
UK private prescription costs typically range from £129 to £320 per month depending on dose and provider, with starter doses at the lower end and maximum doses at the higher end. A full treatment course from starting dose (0.25 mg) to maximum dose (2.4 mg) usually costs between £1,500 and £2,500 over several months. These costs are paid privately — prescriptions are issued by UK-licensed prescribers following an online clinical assessment, and dispensed by GPhC-registered pharmacies. Monthly costs remain consistent once you reach your target maintenance dose.
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 Access vs Private Prescription Route
The NHS has approved semaglutide (Wegovy) through NICE guidance, but access is limited to specialist tier 3 weight management services — not standard GP prescription. Waiting times for NHS specialist services can be months or even years in many regions, with significant variation by region (ICB). Private online prescription is available immediately without NHS referral: you complete a clinical assessment with a UK-licensed prescriber, receive a prescription if appropriate, and collect from a pharmacy. Your GP can still monitor your progress. Both routes require a prescription and clinical assessment confirming you meet eligibility criteria: BMI 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease.
- 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 weight loss should I realistically expect from Wegovy?
Clinical trials showed average weight loss of around 15% of body weight at the maximum dose (2.4 mg) over 68 weeks, alongside diet and exercise. Individual results vary — some people lose 8–10%, others 20% or more. Effectiveness depends on dose, adherence, dietary changes, and personal metabolism. Always use our free GLP-1 weight loss calculator to estimate potential outcomes at different doses based on your current weight.
How much does Wegovy cost per month in the UK?
Private prescription costs typically range from £129 to £320 per month depending on dose — starter doses cost less, maximum doses (2.4 mg) cost more. A full treatment course from 0.25 mg to 2.4 mg usually totals £1,500–£2,500 over several months. Costs are private unless you access through NHS specialist services, where it may be available free if eligible.
Can I get Wegovy on the NHS in the UK?
Yes, but access is limited to specialist tier 3 weight management services, not routine GP prescription. You need referral from your GP and must meet eligibility criteria. Waiting lists vary significantly by region and can be very long. Private prescription is available immediately through online assessment without NHS referral.
How does Wegovy compare to Mounjaro for weight loss?
Both are effective GLP-1-based weight loss injections. Wegovy (semaglutide) is a GLP-1 agonist; Mounjaro (tirzepatide) is a dual GIP/GLP-1 agonist. Clinical trials suggest Mounjaro may produce slightly higher average weight loss (15–21% vs 15%), but differences vary individually. Compare your options using our free weight loss calculator to project outcomes.
Do I need ongoing costs after reaching my target weight?
Most people continue Wegovy to maintain weight loss, as weight typically returns when treatment stops. Monthly costs continue at your maintenance dose. Some people pause treatment after reaching their goal and monitor weight. Discuss long-term plans with your prescriber — whether that's NHS specialist or private — to understand ongoing costs and management.
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.