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 Dose For Weight Loss in the UK
Semaglutide is a weekly weight loss injection licensed in the UK for adults with excess weight and health-related conditions. The standard weight loss dose of semaglutide is 2.4mg once weekly — the maximum approved strength in Wegovy. Dosing starts lower and increases gradually over 16 weeks to allow your body to adjust. This guide explains how semaglutide dosing works under NHS guidance, what the clinical evidence shows, and how to access it in the UK. Try our GLP-1 weight loss calculator above to see how semaglutide might fit into your personal weight management plan.
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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 Dosing Works for Weight Loss
Semaglutide for weight loss starts at a low dose and increases gradually. The standard dosing schedule over 16 weeks is: Week 1–4: 0.25mg, Week 5–8: 0.5mg, Week 9–12: 1mg, Week 13–16: 1.7mg, Week 17 onwards: 2.4mg (maximum). Each dose is a once-weekly injection you give yourself at home. The 2.4mg dose is the full therapeutic dose approved by the MHRA for weight management in the UK. Clinical trial data (STEP-1 trial) showed that adults on semaglutide 2.4mg lost an average of approximately 15% of their body weight over 68 weeks, alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly — some people lose more, some less. Your prescriber may adjust your dosing schedule based on how you respond and any side effects you experience.
- Doses range from 0.25mg to 2.4mg, all given once weekly
- Minimum 4 weeks at each dose before increasing
- Slow dose escalation reduces nausea and stomach side effects
- Some people stay on lower doses if they achieve good results or experience side effects
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 Route for Semaglutide in the UK
In the UK, semaglutide (Wegovy) is available through NHS specialist weight management services or private online prescribing. NHS access requires a referral from your GP to a tier 3 specialist weight management service — availability and waiting times vary significantly by region. NICE has approved semaglutide for use in NHS services for eligible adults. Private access is faster — you can access a UK-licensed prescriber through online platforms following a clinical assessment, and prescriptions are dispensed by GPhC-registered pharmacies. Your GP can advise on NHS pathways in your area. Use our BMI calculator above to check if you might be eligible — adults with BMI 30+ or BMI 27+ with weight-related health conditions may qualify.
- 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 maximum dose of semaglutide for weight loss?
The maximum approved dose of semaglutide (Wegovy) in the UK is 2.4mg, given as a once-weekly injection. This is reached after a 16-week dose escalation schedule starting at 0.25mg. The higher dose is more effective but also carries higher risk of side effects like nausea and diarrhoea. Your prescriber may suggest staying on a lower dose if you experience good results or significant side effects.
How much weight can I expect to lose on semaglutide 2.4mg?
Clinical trials (STEP-1) showed adults on semaglutide 2.4mg lost an average of approximately 15% of body weight over 68 weeks, alongside dietary changes and physical activity. This means someone weighing 100kg might lose around 15kg on average. However, individual results vary — some people lose more, others lose less. Weight loss is not assured and depends on adherence, diet, exercise, and individual metabolism.
How quickly do I reach the full 2.4mg dose?
The standard semaglutide dosing schedule takes 16 weeks to reach 2.4mg. You start at 0.25mg for 4 weeks, then increase every 4 weeks: 0.5mg, 1mg, 1.7mg, then 2.4mg from week 17 onwards. This slow escalation allows your body to adapt and reduces nausea. Some people achieve good weight loss results before reaching maximum dose.
Is semaglutide available on the NHS in the UK?
Yes, semaglutide (Wegovy) is approved by NICE for use in NHS specialist weight management services. Access requires a GP referral to a tier 3 service, and availability varies by region. NHS waiting lists can be long in many areas. Private access is also available through UK-licensed prescribers following an online assessment, with no NHS referral required.
What's the difference between semaglutide and Ozempic?
Both contain semaglutide but are different products. Ozempic (max 2mg) is approved for type 2 diabetes. Wegovy (max 2.4mg) is the licensed weight loss version. Ozempic is not approved for weight loss in the UK — using it off-label for weight loss is not recommended. Always use the medication licensed for your specific condition.
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.