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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Sauna Suit And Weight Loss — What UK Health Evidence Shows
Sauna suits are often marketed as a quick weight loss solution, but the reality is more complex. While they may cause temporary water weight loss through sweating, they do not lead to sustainable fat loss and carry real health risks. For adults in the UK looking for evidence-based weight management, prescription options like Mounjaro and Wegovy, combined with lifestyle changes, offer a safer, more effective approach to losing weight and maintaining it long-term.
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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.
Why Sauna Suits Don't Work For Real Weight Loss
Sauna suits create the illusion of weight loss by forcing rapid fluid loss through sweat. This water weight returns within hours of rehydration — it is not fat loss. The weight you see on the scales is misleading and does not reflect actual changes to your body composition.
More concerning, sauna suits can cause:
- Dangerous dehydration and electrolyte imbalance
- Elevated core body temperature and heat exhaustion
- Increased cardiovascular strain, especially during exercise
- Skin irritation and heat rash
- False sense of progress, delaying real weight management efforts
For sustainable weight loss, you need a calorie deficit over time — not temporary fluid loss. The NHS recommends losing weight at a rate of 0.5 to 1 kg per week through a combination of dietary changes and increased physical activity. Use our free BMI calculator above to assess your current weight status and healthy weight range for your height.
Clinically BackedWeight Loss
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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.
Prescription Weight Management Options Available In The UK
If you have a BMI of 30 or above, or 27 or above with weight-related health conditions like high blood pressure or type 2 diabetes, you may be eligible for prescription weight management medication in the UK.
Currently available options include:
- Mounjaro (tirzepatide) — a once-weekly injection that works as a dual GIP and GLP-1 agonist. Clinical trials showed average weight loss of 15–21% body weight.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection. Evidence suggests average weight loss of around 15% body weight.
- Saxenda (liraglutide) — a once-daily GLP-1 injection, typically used when weekly options are not suitable.
All require a prescription and clinical assessment. Try our GLP-1 weight loss calculator to estimate potential results at different doses, then speak to your GP about whether prescription weight loss medication is appropriate for you.
- 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 sauna suits help with weight loss?
Sauna suits cause temporary water weight loss through sweating, but this returns immediately after rehydration. They do not burn fat or create real weight loss. The NHS advises against relying on sauna suits for weight management due to dehydration risks.
What is the safest way to lose weight in the UK?
The NHS recommends a sustainable approach: a calorie deficit of around 500 kcal per day (achieved through diet and exercise), aiming for 0.5–1 kg weight loss per week. For eligible adults, prescription weight loss medication combined with lifestyle changes is evidence-based and safer than shortcuts like sauna suits.
How do I know if I am eligible for prescription weight loss medication in the UK?
You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions. Use our free BMI calculator to check your current BMI, then contact your GP to discuss whether prescription options like Mounjaro or Wegovy are suitable for you.
What is the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist with an average weight loss of 15–21% body weight. Wegovy (semaglutide) is a GLP-1 agonist only, with average weight loss around 15%. Both are prescription-only, once-weekly injections. Your prescriber will assess which is more appropriate for your individual health.
Can I get prescription weight loss medication through the NHS?
Yes. Mounjaro and Wegovy are available through NHS specialist tier 3 weight management services, though regional availability varies and waiting lists can be long. Private prescription is also available through UK-licensed online prescribers following a clinical assessment. Speak to your GP about your options.
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.