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 Weight Loss Before and After — UK Prescription Options
When you lose weight through prescription medication in the UK, changes often show first in the face. This guide explains how UK-licensed weight management medications like Mounjaro and Wegovy work, who is eligible, and what facial changes you might expect as you progress. We'll cover NHS options, private access, and how to discuss weight loss medication with your GP to understand if it's right for you.
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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-Licensed Weight Management Medications
Three prescription medications are currently licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). In clinical trials, adults using these medications lost an average of 14–21% of their body weight when combined with dietary changes and increased physical activity. Facial fullness often reduces noticeably within the first 8–12 weeks as overall weight decreases. These are GLP-1 (and GIP/GLP-1) receptor agonist medications that work by helping regulate appetite and food intake. Individual results vary significantly depending on starting weight, dose, lifestyle changes, and how long treatment continues. You can calculate your potential weight loss range using our GLP-1 weight loss calculator above, which shows projected outcomes at different doses. Eligibility requires a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea.
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 Prescriptions in the UK
In the UK, prescription weight loss medication is available through two routes. NHS access is through specialist tier 3 weight management services, typically requiring a GP referral—though waiting times vary significantly by region and can be lengthy. Private access is available through GPhC-registered online prescribers following a clinical assessment, without needing an NHS referral. Both routes require a prescriber to confirm you're medically suitable before issuing a prescription. To find out if you're eligible, use our free BMI calculator above to check your current BMI, then discuss your options with your GP. They can advise on NHS referral pathways in your area or discuss whether private prescription weight loss treatment might suit your circumstances. Never start any weight loss medication without a clinical assessment and prescription.
- 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 look different after weight loss with medication?
Yes, facial changes are common and often visible within 8–12 weeks. As overall weight decreases, facial fullness, puffiness, and cheek definition typically change noticeably. The extent varies between individuals and depends on starting weight, genetics, and age. Weight loss also often improves skin texture and reduces water retention in the face.
How much weight do people lose on Mounjaro and Wegovy in the UK?
In clinical trials, Mounjaro users lost an average of 15–21% of body weight, while Wegovy users lost approximately 15% on average, when combined with a reduced-calorie diet and exercise. Individual results vary significantly. Use our GLP-1 weight loss calculator to see projected outcomes at different doses based on your starting weight.
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 27 or above with weight-related health conditions like type 2 diabetes or high blood pressure. Eligibility criteria vary by region. Discuss your options with your GP, who can assess whether you qualify and refer you to specialist services where available.
What's the difference between NHS and private weight loss medication in the UK?
NHS access is through specialist weight management services (usually involving a waiting list and GP referral), while private access is through online prescribers after a clinical assessment. Both require a prescription and clinical suitability check. Private options are available immediately but involve out-of-pocket costs, typically £130–£320 per month depending on dose.
How quickly will I see changes in my face after starting weight loss medication?
Many people notice facial changes within 4–8 weeks of starting medication, though this varies. Facial puffiness and water retention often reduce first, followed by changes in cheek and jawline definition as weight loss progresses. Track your progress using our free progress tracker to monitor changes over time alongside your weight and BMI.
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.