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
Excess Belly Skin After Weight Loss — What You Need to Know
Excess belly skin (sometimes called loose or sagging skin) is a common issue after significant weight loss. It happens because skin loses elasticity after stretching for months or years to accommodate excess weight. While some tightening occurs naturally over time, the speed and extent varies based on age, genetics, how much weight was lost, and how quickly. The good news is that understanding what's happening — and knowing your weight management options in the UK — can help you make informed decisions about your health going forward.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 Prescription Weight Loss Works in the UK
If you're considering further weight loss with medical support, the UK offers several prescription weight management options. These are available through both NHS specialist services and private online prescribing. The main medications are Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide) — all GLP-1 or dual GIP/GLP-1 receptor agonists that help reduce appetite and support sustainable weight management. Clinical trials show these can help adults lose an average of 15–21% of their body weight, though individual results vary.
- Mounjaro: Once-weekly injection, maximum dose 15 mg
- Wegovy: Once-weekly injection, maximum dose 2.4 mg
- Saxenda: Once-daily injection, maximum dose 3 mg
All require a prescription and clinical assessment to confirm eligibility. Use our free GLP-1 weight loss calculator to explore how these medications might help with your weight management goals.
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 vs Private Access — How to Get Started
In the UK, prescription weight loss medication is available through two main routes. NHS access requires referral to a specialist tier 3 weight management service — typically through your GP — though availability and waiting times vary significantly by region. Private access is faster and doesn't require NHS referral; you can have an online consultation with a UK-licensed prescriber and be prescribed medication if clinically appropriate.
To find out if you're eligible, talk to your GP or complete a private online assessment. Your prescriber will consider your BMI, health conditions, and medical history. Calculate your personal BMI using our free BMI calculator above to understand where you stand. Either way, weight management medication works best alongside lifestyle changes — diet and physical activity remain essential.
- 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?
Skin stretches over time to accommodate excess weight. When you lose weight relatively quickly, skin doesn't always tighten at the same pace because elastin and collagen production slows with age and rapid volume loss. Loose skin is especially common after losses of more than 20–30 kg.
Can prescription weight loss medication help with loose skin?
Weight loss medications like Mounjaro and Wegovy help you lose weight sustainably, which may prevent additional loose skin. However, they don't directly tighten existing excess skin. Slower weight loss (around 0.5–1 kg per week) allows skin slightly more time to adapt, which may help.
What options exist for loose skin after weight loss?
Natural tightening occurs gradually over 1–2 years post-weight loss. Building muscle through strength training can help fill out loose skin. For significant excess skin, cosmetic procedures like body contouring or skin tightening are available privately — discuss options with a cosmetic surgeon or dermatologist.
Am I eligible for prescription weight loss treatment in the UK?
UK adults with a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, hypertension, sleep apnoea, cardiovascular disease), may be eligible. Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP or prescriber can assess your individual eligibility.
Should I worry about loose skin when losing weight?
Some loose skin is a natural part of significant weight loss, not a sign anything is wrong. The health benefits of reaching a healthy weight far outweigh cosmetic concerns about loose skin. Talk to your GP if you're worried — they can advise on what to expect and realistic timelines for skin tightening.
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.