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
What Does Semaglutide Do — Cost & Access in the UK
Semaglutide is a GLP-1 receptor agonist injection licensed in the UK as Wegovy for weight management. It works by activating natural hormones that help reduce appetite, increase feelings of fullness, and slow how food moves through your stomach. This medication is prescription-only and requires a clinical assessment before being prescribed. In the UK, you can access semaglutide through NHS specialist weight management services or via private prescription. Costs, eligibility, and availability vary significantly depending on which route you choose. Understanding how semaglutide works and what it costs will help you decide if it's right for your health goals.
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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 Semaglutide Works & What It Costs in the UK
Semaglutide mimics GLP-1, a natural hormone your gut produces after eating. It signals your brain that you're full, reduces food cravings, slows stomach emptying, and helps regulate blood sugar. Weekly weight loss injection doses range from 0.25 mg up to 2.4 mg, with doses increased every 4 weeks under prescriber guidance.
UK private prescription costs: Expect to pay approximately £129–£320 per month, depending on your dose and the provider. Starting doses (0.25–0.5 mg) are typically cheaper; the maximum dose (2.4 mg) is at the higher end. This is for the medication only and may not include the consultation fee. Private prescriptions are issued following an online clinical assessment with a UK-licensed prescriber and dispensed by GPhC-registered pharmacies.
Our GLP-1 weight loss calculator can help you estimate potential weight loss and understand the dose escalation journey.
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 — How to Get Semaglutide
NHS route: Semaglutide (Wegovy) is available through tier 3 specialist weight management services following referral from your GP. However, NHS availability is extremely limited and varies by region—waiting lists can exceed 12 months in many areas. You must meet strict eligibility criteria (BMI ≥30, or ≥27 with weight-related health conditions) and be assessed by a specialist team.
Private route: Faster access without NHS referral. You complete an online consultation with a UK-licensed prescriber who assesses your suitability. If approved, a prescription is issued and dispensed by a registered pharmacy. The entire process typically takes 24–48 hours. Use our BMI calculator to check your eligibility before applying.
- 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 available on the NHS in the UK?
Yes, semaglutide (Wegovy) is available through NHS tier 3 specialist weight management services, but only after GP referral and specialist assessment. Availability is extremely limited, with waiting lists of many months in most areas. You must meet eligibility criteria and be assessed by a multidisciplinary team.
How much does semaglutide cost privately in the UK?
Private semaglutide costs range from approximately £129–£320 per month depending on your dose and provider. Starting doses (0.25–0.5 mg) are cheaper; the maximum dose (2.4 mg) costs more. This is medication cost only and may not include the consultation fee.
How do I get a private prescription for semaglutide in the UK?
Complete an online consultation with a UK-licensed prescriber who will assess your medical history and suitability. If approved, they issue a prescription to a GPhC-registered pharmacy, which dispatches your medication. The process typically takes 24–48 hours from approval.
What's the difference between semaglutide and Ozempic?
Both contain semaglutide but are different medicines. Ozempic (up to 2 mg) is approved for type 2 diabetes. Wegovy (up to 2.4 mg) is the licensed weight management version. Ozempic is not licensed for weight loss in the UK—using it for weight loss is off-label.
Does semaglutide work for weight loss?
Clinical trials showed semaglutide helped participants lose an average of approximately 15% of body weight over 68 weeks alongside diet and exercise. Individual results vary significantly. Weight loss depends on following a reduced-calorie diet and increasing physical activity—the injection supports but doesn't replace these 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.