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
Drinking Warm Water For Weight Loss — And What Actually Works
Drinking warm water is often suggested as a weight loss aid, and whilst staying hydrated is important for health, the evidence for warm water alone is limited. If you're serious about weight management in the UK, prescription medications like Mounjaro and Wegovy have strong clinical evidence behind them. This guide explains what hydration can do, and more importantly, what prescription weight loss options are available to eligible adults through the NHS or private prescribing.
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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 — What the Evidence Shows
Whilst drinking enough water supports metabolism and can help you feel fuller, prescription weight loss medications offer significantly stronger results for eligible adults. Three GLP-1 and GIP/GLP-1 medications are licensed in the UK:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 agonist. Clinical trials showed participants lost an average of 15–21% of their body weight alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 agonist. The STEP trial demonstrated approximately 14.9% average weight loss at the maximum dose.
- Saxenda (liraglutide) — a daily GLP-1 injection with evidence supporting approximately 5–clinically studied weight loss on average.
All three are prescription-only and require a clinical assessment to confirm eligibility. Use our free GLP-1 weight loss calculator above to explore potential outcomes at different doses.
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 and Private Prescribing — How to Get Started
In the UK, you can access prescription weight loss medication through two routes:
- NHS: Referral to a tier 3 specialist weight management service (ask your GP). Availability and waiting times vary significantly by region, with some areas having long waiting lists.
- Private: Online consultation with a UK-licensed prescriber. Available without NHS referral, typically faster, with costs ranging £129–£320 per month depending on dose.
Both routes require a clinical assessment confirming your BMI and any weight-related health conditions. Your GP can give personalised advice about whether you're eligible and which option suits you best. Check your BMI using our calculator above.
- 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.
Does drinking warm water actually help with weight loss?
Drinking water (warm or cold) supports hydration and may slightly boost metabolism. However, the effect is modest. For meaningful weight loss, you need a sustained calorie deficit plus lifestyle changes. Prescription medications like Mounjaro and Wegovy have far stronger clinical evidence for weight management.
What's the difference between Mounjaro and Wegovy for weight loss?
Mounjaro is a dual GIP/GLP-1 agonist; Wegovy is GLP-1 only. Clinical trials showed Mounjaro achieved slightly higher average weight loss (15–21% vs 14.9% for Wegovy). Both are once-weekly injections. Individual results vary significantly, and a prescriber will advise which is suitable for you.
Can I get Mounjaro or Wegovy on the NHS?
Yes, both are available on the NHS through specialist tier 3 weight management services. Access requires a GP referral and assessment. Availability and waiting times vary by region (ICB). Many areas have long waiting lists. Private prescribing offers faster access if you're eligible and can pay.
Who is eligible for prescription weight loss medication in the UK?
Generally, adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, sleep apnoea, etc.). Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP or prescriber will assess your individual eligibility.
How much does prescription weight loss medication cost privately?
Costs vary by provider and dose. Typically £129–£320 per month for Mounjaro or Wegovy. Each dose is adjusted over 4-week increments, so monthly costs may vary as you titrate to your maintenance dose. Always check current pricing with your chosen prescriber.
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.