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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Face Slim After Weight Loss — UK Medication Guide
Significant weight loss often leads to noticeable changes in facial appearance, including reduced puffiness, more defined cheekbones, and a slimmer jawline. For men considering weight management in the UK, prescription medications like Mounjaro and Wegovy are now available alongside lifestyle changes. This guide explains how to lose weight effectively, the medication options available, and how to find out if you're eligible for NHS or private support. Individual results vary, but even modest weight loss can create visible facial changes whilst improving your health.
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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.
Prescription Weight Loss Options Available in the UK
Three main GLP-1 and GIP/GLP-1 medications are licensed for weight management in the UK:
- Mounjaro (tirzepatide) — A once-weekly injection that activates two hormone pathways (GIP and GLP-1). Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks, though individual results vary significantly.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. In clinical trials, participants lost approximately 15% of their body weight on average, alongside a reduced-calorie diet and increased physical activity.
- Saxenda (liraglutide) — A daily GLP-1 injection with similar effectiveness to Wegovy.
All three are prescription-only medicines requiring a clinical assessment before being prescribed. They work by reducing appetite, helping you feel fuller, and supporting sustainable weight loss. A prescriber will assess whether prescription weight loss medication is suitable for you based on your health history and BMI.
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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 in the UK
NHS access: Prescription weight loss medications are available through specialist tier 3 weight management services. Your GP can refer you if you meet eligibility criteria (typically BMI 30 or above, or BMI 27+ with weight-related health conditions). However, waiting times vary significantly by region, and access is not available in all areas.
Private access: These medications are available through private prescribers following an online clinical assessment. You don't need an NHS referral, making it faster to start treatment. Costs vary by dose and provider.
To find out if you're eligible, use our free BMI calculator above to check your personal BMI, then speak with your GP or a licensed prescriber about your options for weight management in the UK.
- 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.
Will my face slim down with weight loss?
Yes, most men notice facial changes with significant weight loss, including reduced cheek puffiness, more defined jawline, and sharper cheekbones. The extent depends on genetics, age, and how much weight you lose. Even a 5–10% reduction in body weight can produce visible facial changes.
How much weight do Mounjaro and Wegovy help you lose?
In clinical trials, Mounjaro helped participants lose an average of 15–21% of body weight, whilst Wegovy showed approximately 15% average loss. However, individual results vary considerably. These medications work alongside a reduced-calorie diet and increased physical activity — they're not a substitute for lifestyle changes.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea, cardiovascular disease). Speak with your GP about referral to a specialist weight management service, though availability varies by region.
Can I get Mounjaro or Wegovy privately in the UK?
Yes. Both medications are available through private prescribers following an online clinical assessment. You don't require an NHS referral. A licensed UK prescriber will assess whether the medication is suitable for you. Costs vary but typically range from £130–£300+ per month depending on dose.
How long does it take to see facial changes with weight loss?
Visible facial changes typically appear after losing 5–10% of your body weight, which may take 8–12 weeks depending on your starting weight and rate of loss. The NHS recommends losing 0.5–1 kg per week for sustainable results. Our free progress tracker can help you monitor your journey.
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.