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
Semaglutide Dosage for Weight Loss in the UK
Semaglutide is a prescription-only weight loss injection licensed in the UK, marketed as Wegovy. The medication is administered as a once-weekly injection that starts at a low dose and gradually increases over several weeks. Understanding the dosage schedule, NHS eligibility criteria, and what clinical trial results show is essential for anyone considering this treatment. Our GLP-1 weight loss calculator can help you estimate potential outcomes at different dose levels based on UK data.
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 Dosage Schedule and NHS Eligibility in the UK
Semaglutide dosage for weight loss follows a structured escalation schedule designed to minimise side effects whilst maximising effectiveness. Starting at 0.25 mg weekly, the dose increases by 0.25 mg every four weeks until reaching the maximum maintenance dose of 2.4 mg weekly. This gradual approach, tested in the STEP-1 clinical trial, helps the body adjust to the medication.
- Weeks 1–4: 0.25 mg once weekly
- Weeks 5–8: 0.5 mg once weekly
- Weeks 9–12: 1.0 mg once weekly
- Weeks 13–16: 1.7 mg once weekly
- Week 17+: 2.4 mg once weekly (maintenance)
For NHS prescription in the UK, adults must have a BMI of 30 kg/m² or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, hypertension, or sleep apnoea. South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds due to increased health risks at lower weights. Access is through tier 3 specialist weight management services, not standard GP prescriptions. Use our free BMI calculator to check your personal BMI category and understand your eligibility.
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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 Route for Semaglutide in the UK
NHS semaglutide access is available through specialist weight management services but involves referral from your GP and significant regional variation in availability. Waiting times can range from several months to over a year in many areas. Private prescribing is available immediately through GPhC-registered online pharmacies following a clinical assessment, with costs typically ranging from £129–£200 per month depending on dose.
The STEP-1 trial showed average weight loss of approximately 14.9% body weight at 68 weeks on 2.4 mg semaglutide alongside dietary changes and increased physical activity. Clinical trial data demonstrates the benefit of this weekly weight loss injection, though individual results vary significantly. Always discuss with your GP or prescriber whether semaglutide is suitable for your personal health situation. Track your progress with our free progress tracker once treatment begins.
- 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 is the starting dose of semaglutide for weight loss in the UK?
The starting dose is 0.25 mg once weekly. This low initial dose helps your body adjust to the medication and minimises nausea and other side effects. The dose then increases gradually every four weeks until reaching 2.4 mg weekly, which is the maximum licensed dose for Wegovy in the UK.
How long does it take to reach the maximum semaglutide dose?
It takes approximately 16–20 weeks to reach the maximum dose of 2.4 mg if escalation continues without interruption. Each dose is held for a minimum of four weeks before increasing. Your prescriber may adjust this timeline based on how well you tolerate the medication.
Can I get semaglutide on the NHS for weight loss in the UK?
Yes, semaglutide (Wegovy) is available on the NHS through tier 3 specialist weight management services, but access requires GP referral and eligibility assessment. You must have a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Availability varies significantly by region, and waiting times can be lengthy.
What weight loss can I expect from semaglutide at 2.4 mg weekly?
Clinical trial data from STEP-1 showed average weight loss of approximately 14.9% body weight at 68 weeks on the 2.4 mg dose. Results vary between individuals based on genetics, lifestyle changes, and adherence. Our GLP-1 weight loss calculator can provide personalised estimates based on your starting weight.
Is semaglutide the same as Ozempic?
Both contain the same active ingredient, semaglutide, but they are different medications for different purposes. Wegovy is specifically licensed for weight loss at doses up to 2.4 mg. Ozempic is approved for type 2 diabetes at lower doses and is not licensed for weight loss in the UK, making this GLP-1 receptor agonist choice important for weight 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.