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
What Is Mounjaro Face?
"Mounjaro face" is a term some people use to describe facial changes that may occur during weight loss with tirzepatide, the active ingredient in Mounjaro. These changes can include loss of facial volume, more visible cheekbones, or a hollowed appearance. This is not a unique side effect of Mounjaro — it's a natural consequence of significant weight loss. Understanding what to expect can help you prepare and make informed decisions about treatment.
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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.
Why Does Facial Change Happen During Weight Loss?
When you lose weight, your body loses fat from all areas, including your face. The face contains significant fat deposits under the skin that contribute to volume and fullness. As these deposits reduce during weight loss — whether through diet, exercise, or medications like tirzepatide (the active ingredient in Mounjaro) — facial features can become more defined or angular.
- Fat redistribution: Your body doesn't control where fat is lost from first; it depends on genetics and individual factors
- Age factor: Younger skin may bounce back more easily; older skin may show more visible changes
- Rate of loss: gradual weight management may produce more noticeable facial changes than gradual loss
- Individual variation: Some people experience minimal facial changes while others notice more significant differences
This is not a side effect specific to Mounjaro or GLP-1 receptor agonist medications — it's a natural physiological response to weight loss itself.
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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.
Managing Facial Changes During Weight Loss
If you're concerned about facial changes while using Mounjaro, several strategies may help. Maintaining good hydration supports skin elasticity and overall health. A protein-rich diet during weight loss helps preserve muscle mass, which can help maintain facial structure. Skincare routines with moisturisers and sun protection may help skin adapt to changes. Weight loss at a moderate pace — the NHS recommends 0.5 to 1 kg per week — allows your skin time to adjust gradually. If you experience significant concerns about facial appearance, speak with your GP or a dermatologist, who can discuss additional options.
- 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.
Is "Mounjaro face" a real side effect?
"Mounjaro face" is not a medical term or listed side effect. It's a colloquial description of facial volume loss that occurs during weight loss with any method, including Mounjaro. The facial changes happen due to fat loss, not the medication itself. This occurs with any significant weight loss.
Can I prevent facial changes while taking Mounjaro?
You can't entirely prevent facial changes during weight loss, but you can minimise them by losing weight gradually (0.5–1 kg per week per NHS guidance), staying hydrated, eating adequate protein, and maintaining a skincare routine. Slower, steadier weight loss allows skin to adjust more gradually.
Will my face return to normal after I stop Mounjaro?
Once weight is stabilised and you stop losing weight, no further facial volume loss will occur. However, lost facial fat doesn't typically return unless you regain the weight. Some people regain weight after stopping Mounjaro; others maintain their new weight. Results vary individually.
Does Mounjaro cause more facial changes than other weight loss methods?
No — facial changes during weight loss are proportional to how much weight you lose, not the method used. Whether weight loss comes from diet, exercise, Mounjaro, or Wegovy, facial volume loss occurs at similar rates. The tirzepatide in Mounjaro doesn't cause unique facial effects.
Should I be concerned about "Mounjaro face" when considering treatment?
Facial changes are a normal consequence of weight loss, not a serious concern. If you're considering Mounjaro, discuss your concerns with your GP or prescriber. The health benefits of weight loss typically far outweigh cosmetic changes. Many people feel their appearance improves overall despite facial volume loss.
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.