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 Happens to Your Face When You Lose Weight?
When you lose weight, your face often changes noticeably — but this happens gradually over weeks and months, not overnight. The skin on your face, cheeks, and jawline adjust as fat deposits decrease, which can make your features appear sharper and more defined. This is a natural and common part of sustainable weight loss. Understanding what to expect helps you set realistic goals and appreciate the health benefits alongside any visible changes. Our free BMI calculator can help you establish a baseline for your current weight, whilst our GLP-1 weight loss calculator shows projected changes if you're considering prescription weight management options.
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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 Facial Changes Occur During Weight Loss
Weight loss in the face happens because subcutaneous fat (the fat stored just beneath the skin) is metabolised when your body enters a calorie deficit. This fat is distributed across your entire body, including your cheeks, jawline, forehead, and around your eyes. As it reduces, the underlying bone structure becomes more visible, creating a more defined appearance.
- Cheeks: Lose fullness first, creating more prominent cheekbones
- Jawline: Becomes sharper and more defined as chin fat decreases
- Under-eyes: Puffiness may reduce, though sometimes fine lines become more visible
- Forehead: May appear broader as temple fat decreases
The rate of facial change depends on your starting weight, age, genetics, and how quickly you lose weight. Slower, sustainable weight loss (0.5–1 kg per week, as NHS guidance recommends) allows your skin to adjust gradually, reducing the risk of loose skin. Faster weight loss may cause more noticeable changes but can affect skin elasticity.
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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.
Facial Changes and Weight Loss Medication
If you're considering prescription weight loss medication like Wegovy (semaglutide) or Mounjaro (tirzepatide) through NHS weight management services or private prescription options, facial changes occur alongside overall body weight reduction. Clinical trials show Wegovy helps participants lose around 15% of body weight on average, with individual results varying significantly. Facial changes become visible after 8–12 weeks of consistent use.
It's important to remember that facial appearance is just one benefit of weight loss — the primary advantages are improved health outcomes. Use our free BMI calculator to check your current weight status, and our weight loss calculator to estimate potential changes with prescription medication. Always consult your GP or a licensed prescriber before starting any weight loss treatment.
- 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.
How long does it take to see facial changes when losing weight?
Most people notice subtle facial changes after 4–6 weeks of weight loss, with more noticeable definition appearing by 8–12 weeks. This depends on how much weight you're losing per week and your starting point. Gradual, sustainable loss allows skin to adjust better.
Will my face look loose or saggy after weight loss?
gradual weight management can sometimes cause temporary skin looseness, particularly if you lose more than 1.5 kg per week. Slower loss (0.5–1 kg weekly) gives skin time to adjust. Hydration, strength training, and sun protection also help maintain skin elasticity during weight loss.
Does facial fat return if you regain weight?
Yes, facial fat distribution can return if weight is regained. This is why sustainable lifestyle changes are more effective than gradual weight management. If using prescription medication, maintaining healthy habits after treatment is important for long-term results.
Can weight loss medication cause specific facial changes?
GLP-1 medications like Wegovy support overall weight loss, which includes facial fat reduction. There are no medication-specific facial effects beyond what occurs during normal weight loss. Individual variation is significant — some people notice face changes before body changes, others later.
Should I consider cosmetic procedures after significant weight loss?
This is a personal choice best discussed with your GP or a dermatologist. Most facial changes settle within 6–12 months of reaching a stable weight. Non-invasive options exist if you're concerned, but many people find their appearance improves naturally as skin adjusts.
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.