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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Does lukewarm water help in weight loss?
Drinking lukewarm water is often suggested as a natural weight loss aid, but the evidence is mixed. While staying hydrated supports overall health and can help you feel fuller between meals, lukewarm water alone is unlikely to produce significant weight loss. If you're looking for NHS-approved weight management support in the UK, prescription options are available for eligible adults. This guide explains what science shows about water and weight, plus your options for prescription weight loss medication that have proven clinical evidence.
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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.
Prescription weight loss options available in the UK
For adults struggling with weight management in the UK, prescription weight loss medications are available through both NHS specialist services and private prescribing. The three main UK-licensed options are:
- Mounjaro (tirzepatide) — a once-weekly injection that activates two natural hormone pathways (GIP and GLP-1), helping reduce appetite and support fuller feeling after meals. Clinical trials showed average weight loss of around 15–21% of body weight at the highest dose.
- Wegovy (semaglutide) — a once-weekly GLP-1 injection that works on a single hormone pathway. Clinical evidence shows average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — a daily GLP-1 injection option, though less commonly prescribed than the once-weekly alternatives.
All three are prescription-only and require a clinical assessment before being prescribed. They work best alongside a reduced-calorie diet and increased physical activity — medication alone is not effective without lifestyle changes.
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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.
NHS eligibility and next steps
In the UK, you may be eligible for prescription weight loss medication if you have a BMI of 30 or above, or a BMI of 27–29.9 with a weight-related health condition (such as type 2 diabetes, high blood pressure, or sleep apnoea). Lower BMI thresholds apply if you're of South Asian, Chinese, Black African, or Black Caribbean heritage.
To explore your options, start a conversation with your GP, who can refer you to a specialist weight management service (available through NHS) or discuss private prescribing routes. Use our free BMI calculator above to check your current BMI, and our GLP-1 weight loss calculator can help you understand potential outcomes at different medication doses. Your GP can then assess whether prescription weight loss is right for your individual health situation.
- 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 lukewarm water before meals help with weight loss?
Drinking water before meals can help you feel fuller and eat less, potentially supporting weight management. However, water temperature (lukewarm vs cold) makes minimal difference to weight loss. Staying hydrated is important for overall health, but it's not a replacement for calorie deficit, diet changes, or prescription support if needed.
What does science say about water and weight loss?
Research shows that drinking water increases energy expenditure slightly and can reduce appetite temporarily. However, the effect is modest. One litre of water per day is unlikely to produce meaningful weight loss on its own. Weight loss requires a sustained calorie deficit achieved through diet, activity, and sometimes medication.
How does prescription weight loss medication compare to natural methods?
Prescription medications like Mounjaro and Wegovy have strong clinical evidence — producing 15–21% average weight loss in trials. Natural methods like water intake have minimal direct weight loss impact. However, medication works best combined with healthy eating and activity. If you're eligible, prescription options offer far more substantial support than water alone.
What weight loss results can I expect with prescription medication in the UK?
With Mounjaro, average weight loss is approximately 15–21% of body weight, depending on dose. Wegovy shows similar results (around 15% average). Individual results vary significantly. Your GP or prescriber can assess whether you're eligible and what realistic outcomes might be for you based on your health situation.
How do I find out if I'm eligible for weight loss medication on the NHS?
Start by speaking to your GP about weight management options. They can check your BMI and assess whether specialist referral is appropriate. NHS availability varies by region, so waiting times differ. Private prescribing is also available if you meet eligibility criteria. Use our BMI calculator above to get a starting point for your conversation with your GP.
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.