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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Sweat Suits for Weight Loss — Do They Work?
Sweat suits are often marketed as weight loss aids, but the evidence doesn't support their use for sustainable fat loss. They may cause temporary water weight loss through perspiration, but this weight returns when you rehydrate. If you're looking for effective weight management in the UK, prescription medications and lifestyle changes are proven approaches. The NHS and health experts recommend evidence-based methods that actually work long-term. This guide explores why sweat suits fall short and what genuinely helps with weight loss.
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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.
Evidence-Based Weight Loss Options Available in the UK
If you're struggling with weight management, the NHS and private healthcare offer several prescription options that have strong clinical evidence behind them:
- Mounjaro (tirzepatide) — A once-weekly injection licensed for weight management. Clinical trials showed an average weight loss of 15–21% of body weight when combined with lifestyle changes. It's a dual GIP and GLP-1 receptor agonist that helps reduce appetite and food cravings.
- Wegovy (semaglutide) — Another once-weekly GLP-1 injection approved in the UK. Average weight loss in trials was around 15% of body weight alongside diet and physical activity. Available through NHS specialist services or private prescription.
- Saxenda (liraglutide) — A daily GLP-1 injection option for weight management in eligible adults.
Unlike sweat suits, these medications work by targeting the biological pathways that control appetite and metabolism. Individual results vary, and prescribers assess eligibility based on your BMI and health status.
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.
How to Find Out If You're Eligible for Prescription Weight Loss Treatment
NHS route: Speak to your GP about referral to a specialist weight management service. Eligibility typically includes adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Waiting lists vary by region, but the NHS is expanding access to weight loss injections.
Private route: If you prefer faster access, GPhC-registered online prescribers can assess you for prescription weight loss medication without an NHS referral. Check your BMI using our free BMI calculator to understand where you stand, and discuss options with a qualified prescriber who will determine suitability based on your individual health profile.
- 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.
Do sweat suits actually help you lose weight?
No. Sweat suits cause temporary water loss through perspiration, which returns immediately when you drink. They don't burn fat or create lasting weight loss. This water weight loss can be dehydrating and offers no metabolic benefit. Evidence-based approaches like diet, exercise, and medication work far better for sustainable weight loss.
What's the difference between water weight loss and fat loss?
Water weight is temporary — it returns within hours of rehydration. Fat loss happens when you consistently maintain a calorie deficit. One kilogram of fat loss requires approximately a 7,700 calorie deficit. Sweat suits only cause water loss, not fat loss. Real weight management requires lifestyle changes or evidence-based medication.
Are prescription weight loss injections available on the NHS in the UK?
Yes. Mounjaro, Wegovy, and Saxenda are all licensed for weight management in the UK. NHS access is through specialist tier 3 weight management services, typically after GP referral. Availability and waiting times vary by region. Private prescription is also available through online healthcare providers for those seeking faster access.
What's the eligibility for prescription weight loss medication in the UK?
Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions, may be eligible. Weight-related conditions include type 2 diabetes, prediabetes, high blood pressure, and sleep apnoea. Lower BMI thresholds may apply for people of South Asian, Chinese, Black African, or Black Caribbean heritage. Your GP or prescriber assesses individual eligibility.
How much weight can you expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight with Mounjaro and around 15% with Wegovy, achieved alongside reduced-calorie diet and increased physical activity. Individual results vary significantly — some people lose more, some less. Try our free GLP-1 weight loss calculator to see projected outcomes at different doses based on your starting weight.
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.