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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Managing Loose Skin After Weight Loss in the UK
Loose skin after significant weight loss is common, especially when weight drops quickly. If you're considering prescription weight management options in the UK — such as Mounjaro, Wegovy, or other GLP-1 medications — it's helpful to understand what to expect for your skin as you lose weight. This guide covers UK-licensed prescription options, eligibility criteria, and practical steps to support skin health during your weight loss journey.
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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 Medications and Skin Health
Mounjaro (tirzepatide) and Wegovy (semaglutide) are prescription-only GLP-1 medications licensed in the UK for weight management in eligible adults. Clinical trials show these medications support weight loss of 15–21% of body weight on average when combined with diet and exercise changes. Faster weight loss increases the likelihood of loose skin because skin has less time to adjust and retract naturally. Saxenda (liraglutide) is another UK-licensed GLP-1 option (daily injection rather than weekly).
Eligibility for prescription weight loss medication in the UK includes:
- BMI of 30 kg/m² or above, or
- BMI of 27–29.9 kg/m² with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea
- Lower thresholds apply for adults of South Asian, Chinese, Black African, or Black Caribbean heritage
Prescription weight loss injections work best alongside sustained dietary changes and increased physical activity. Individual results vary, and your GP or a licensed prescriber will assess whether this medication is suitable for you based on your personal health profile.
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 Options and Skin Care Support
NHS access to prescription weight loss medication is through tier 3 specialist weight management services — referral from your GP is typically required, though availability and waiting times vary significantly by region. Private access is available through GPhC-registered online prescribers without an NHS referral, though costs apply.
Regardless of how you access weight loss medication, supporting your skin health during gradual weight management is important. Staying well-hydrated, eating adequate protein, gradually increasing physical activity, and maintaining skin moisture with appropriate skincare products can all help minimise loose skin appearance. Our free BMI calculator and GLP-1 weight loss calculator can help you understand your starting point and projected weight loss ranges — use these alongside conversations with your GP or prescriber to plan realistic expectations for your weight loss journey.
- 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 prescription weight loss medication definitely cause loose skin?
No. Loose skin risk depends on how much weight you lose, how quickly you lose it, your age, genetics, and skin elasticity. Slower weight loss and younger skin typically show better natural retraction. Medication-supported weight loss combined with strength training and hydration can help minimise loose skin appearance.
What's the difference between Mounjaro and Wegovy for weight loss?
Both are prescription-only weekly injections licensed for UK weight management. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with average weight loss of 15–21% in trials. Wegovy (semaglutide) is a GLP-1 agonist with average weight loss around 15%. Both require clinical assessment. Your prescriber will advise which is appropriate for you.
Can I get prescription weight loss medication on the NHS?
Yes, through NHS tier 3 specialist weight management services following a GP referral. However, waiting times and availability vary significantly across UK regions. Private online prescribing options are also available without NHS referral, though these involve costs. Your GP can advise on NHS eligibility and local pathways.
How can I prevent or minimise loose skin during weight loss?
Gradual weight loss (0.5–1kg per week), adequate protein intake, strength training to preserve muscle, staying hydrated, and moisturising skin regularly all help. Avoiding very gradual weight management without medical supervision is also important. Our progress tracker can help you monitor sustainable weight loss rates.
Should I wait for loose skin to resolve before seeking weight loss treatment?
No. Starting weight loss medication and lifestyle changes now is more beneficial for your overall health than delaying. Loose skin often improves naturally over 1–2 years post-weight loss. Your GP can discuss realistic timelines and whether any cosmetic options are relevant after significant weight loss is achieved.
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.