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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Weight Loss Face Before And After — Understanding Facial Changes
Weight loss often leads to visible changes in facial appearance as the body reduces fat stores from all areas, including the face and cheeks. If you're interested in weight management through prescription medication available in the UK, there are several evidence-based options. This guide explains how facial changes occur during weight loss and explores prescription weight loss injections like Mounjaro and Wegovy, which may help you achieve sustainable results alongside diet and lifestyle changes.
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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.
UK Prescription Weight Loss Options
Three main prescription weight management medications are licensed in the UK for eligible adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). Mounjaro works as a dual GIP and GLP-1 receptor agonist and in clinical trials showed an average weight loss of around 15–21% of body weight. Wegovy is a once-weekly GLP-1 injection with average weight loss of approximately 15% based on clinical evidence. Saxenda is a daily injection with similar outcomes.
Eligibility in the UK typically requires a BMI of 30 or above, or 27 or above with weight-related health conditions like type 2 diabetes, high blood pressure, or sleep apnoea. As weight decreases, you may notice gradual facial reshaping — cheekbones becoming more defined, reduced puffiness, and a more contoured jawline. Individual results vary significantly.
Use our free BMI calculator above to check your personal BMI, and our GLP-1 weight loss calculator can help estimate potential weight loss at different medication doses.
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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.
Getting Started: NHS and Private Access
In the UK, prescription weight loss medication is available through two routes. NHS access requires referral to a specialist tier 3 or tier 4 weight management service by your GP — availability varies by region and waiting lists can be lengthy. Private access is available through a GPhC-registered online pharmacy following a clinical assessment with a UK-licensed prescriber, without needing an NHS referral.
Facial changes during weight loss depend on how much weight you lose, how quickly, and your individual genetics. Most noticeable changes appear after losing 5–10% of body weight. To find out if prescription weight loss medication is right for you, speak to your GP about your weight management goals and health concerns. They can assess your eligibility or refer you to specialist services. Track your progress with our free progress tracker to monitor both weight loss and other health improvements over time.
- 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 definitely change if I lose weight?
Most people notice some facial changes with significant weight loss, including reduced cheek fullness, more defined cheekbones, and a more contoured jawline. However, the extent varies based on genetics, age, skin elasticity, and how much weight is lost. Factors like hydration and sun exposure also affect skin appearance. Results are individual.
Which UK weight loss medication causes the most facial changes?
All three UK-licensed medications (Mounjaro, Wegovy, and Saxenda) work by supporting weight loss, and facial changes follow from overall weight reduction — not from the medication itself. Clinical trials show Mounjaro may produce slightly higher average weight loss percentages than Wegovy, but individual results vary significantly. Your GP can discuss which is most suitable.
How long does it take to see facial changes with weight loss medication?
Facial changes typically become visible after losing 5–10% of body weight, which may take several months depending on your dose and lifestyle factors. Most people see gradual changes over 3–6 months of consistent weight loss. Patience and realistic expectations are important — sustainable weight loss is typically 0.5–1 kg per week.
Am I eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea, etc.). South Asian, Chinese, Black African, and Black Caribbean adults may qualify at lower BMI thresholds. Your GP or a licensed prescriber can assess your eligibility following a clinical consultation.
Can I get weight loss injections through the NHS?
Yes, prescription weight loss medications are available through NHS specialist tier 3 and tier 4 weight management services, though availability and waiting times vary significantly by region. You'll need a GP referral. Alternatively, private access is available through GPhC-registered online pharmacies following a clinical assessment with a UK-licensed prescriber.
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.