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
Loose Tummy Skin After Weight Loss — Why It Happens
Loose or sagging skin after significant weight loss is a common concern, especially around the stomach, arms, and thighs. Your skin has stretched over time to accommodate the extra weight. When you lose weight quickly or lose a large amount, your skin may not have time to retract fully, leaving loose folds. This is a normal physiological response and doesn't mean weight loss has failed — in fact, it's a sign your body has changed significantly. Understanding what causes loose skin and how to minimise it can help you make informed decisions about your weight management journey in the UK.
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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 Weight Loss Options to Minimise Loose Skin
Loose skin is more likely with gradual weight management (more than 1.5 kg per week) and large weight reductions (over 25% of body weight). The NHS recommends slower, sustainable weight loss of 0.5–1 kg per week, which allows your skin more time to adapt. Prescription weight management options in the UK — including Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide) — work alongside diet and exercise to create gradual weight loss rather than extreme calorie restriction. This approach may help preserve skin elasticity during your weight loss journey. Adults with a BMI of 30 or above, or 27 and above with weight-related health conditions, may be eligible for prescription weight loss medication through the NHS or private prescribing. Use our free GLP-1 weight loss calculator to explore projected results at different doses — gradual loss tends to result in better skin outcomes than crash dieting.
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.
Finding Your Weight Management Support in the UK
The best approach to minimising loose skin is gradual weight loss combined with strength training, which helps preserve muscle mass and supports skin firmness. Staying hydrated and maintaining adequate protein intake also support skin health. If you're considering prescription weight loss medication like Mounjaro or Wegovy for sustainable weight management, speak to your GP about referral to an NHS specialist tier 3 weight management service, or explore private prescribing options through a UK-licensed healthcare provider. A clinical assessment will determine whether you're eligible and which option suits your health needs. Track your progress with our free progress tracker, and calculate your BMI using our BMI calculator to understand your starting point and set realistic goals.
- 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.
Why does loose skin happen after weight loss?
Your skin stretches to accommodate excess weight over time. When you lose weight, especially rapidly or in large amounts, your skin has less time to shrink back. Collagen and elastin fibres take time to regenerate. Skin elasticity also declines with age, making loose skin more likely in older adults. Gradual weight loss gives skin more time to adapt naturally.
Can prescription weight loss medication prevent loose skin?
Prescription medications like Mounjaro and Wegovy support gradual weight loss rather than extreme calorie restriction, which may help preserve skin elasticity better than gradual weight management. However, loose skin is a natural consequence of significant weight reduction regardless of method. Combining weight loss medication with strength training and hydration provides the best outcome for skin health.
How long does it take for loose skin to tighten after weight loss?
Skin retraction can take 1–2 years after weight loss, and improvement continues gradually. Younger people typically experience better skin recovery due to higher collagen production. Maintaining weight loss, exercising, staying hydrated, and eating adequate protein all support skin tightening. Some loose skin may become permanent if the weight loss is very large.
What can I do to minimise loose skin while losing weight?
Lose weight gradually (0.5–1 kg per week) rather than rapidly. Build muscle through resistance training to fill areas under loose skin. Stay hydrated, eat adequate protein, and use moisturiser regularly. Avoid yo-yo dieting, which stresses skin repeatedly. Prescription weight loss options in the UK support steady loss, which is gentler on skin than extreme dieting.
Should I consider surgery for loose skin after weight loss?
Loose skin surgery (body contouring) is available privately in the UK, but it's costly and involves risks like scarring. Most people see improvement without surgery over 1–2 years. Discuss concerns with your GP, who can refer you to NHS plastic surgery if loose skin is causing genuine health issues like skin irritation or infection underneath the fold.
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.