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
Does Drinking Water Help With Weight Loss?
Drinking water can support weight management, but it's not a standalone solution for significant weight loss. Water helps reduce hunger, boosts metabolism slightly, and replaces high-calorie drinks — all useful habits alongside a reduced-calorie diet. However, if you're looking for more structured weight loss support in the UK, prescription medications like Mounjaro and Wegovy are available for eligible adults. These work alongside lifestyle changes, including proper hydration, to help achieve meaningful results. Your GP can assess whether you qualify.
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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.
How Water Supports Weight Management
Drinking water supports weight management in several practical ways. Reduces perceived hunger: A glass of water before meals can create a feeling of fullness, helping you eat smaller portions. Replaces sugary drinks: Swapping fizzy drinks, juices, and sweetened coffee for water eliminates hundreds of empty calories daily. Boosts metabolism: Drinking water temporarily increases energy expenditure — a process called thermogenesis — though the effect is modest. Prevents fluid retention: Proper hydration helps your body regulate fluid balance more efficiently.
- Aim for 6–8 glasses daily (around 1.5–2 litres) according to NHS guidance
- Drink water before meals to help with portion control
- Replace sugary drinks with water to cut calorie intake
- Keep a water bottle with you to build the habit
Water is free, has zero calories, and is essential for health — but sustainable weight loss requires a calorie deficit through diet and physical activity as well.
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.
UK Weight Loss Medication — If You Need More Support
If lifestyle changes alone aren't delivering results, prescription weight loss medications available in the UK may help. Mounjaro (tirzepatide) and Wegovy (semaglutide) are GLP-1 and dual GIP/GLP-1 receptor agonists that reduce appetite and support feeling fuller — working alongside proper nutrition and hydration. Saxenda (liraglutide) is another option for eligible adults.
- Available through NHS specialist weight management services or private prescribing
- Eligible adults have a BMI of 30 or above, or 27+ with weight-related health conditions
- Require a prescription from a UK-licensed healthcare professional
- Work best with reduced-calorie diet and physical activity
Check your BMI using our free BMI calculator above, then speak to your GP about whether weight loss medication might be suitable 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.
Does drinking water alone cause weight loss?
No. Water alone doesn't cause weight loss, but it supports weight management by reducing hunger and replacing high-calorie drinks. Meaningful weight loss requires a calorie deficit through diet and physical activity. Water is a useful habit to combine with other healthy changes.
How much water should I drink daily for weight loss?
The NHS recommends about 6–8 glasses of fluid daily (roughly 1.5–2 litres). Drinking water before meals can help with portion control, but there's no clinically supported amount for weight loss — consistent hydration is what matters alongside a reduced-calorie diet.
Can I get prescription weight loss medication on the NHS in the UK?
Yes. Adults with a BMI of 30 or above, or 27+ with weight-related health conditions, may be eligible for prescription weight loss treatment through NHS tier 3 specialist weight management services. However, waiting lists vary by region. Your GP can discuss eligibility and refer you.
What's the difference between NHS and private weight loss medication in the UK?
NHS access is through specialist tier 3 services via GP referral, with variable waiting times by region. Private prescribing is faster and doesn't require a referral, but involves a cost (typically £129–£320 monthly). Both routes require a clinical assessment by a UK-licensed prescriber.
How can I check if I'm eligible for weight loss medication?
Use our free BMI calculator on this page to check your BMI. If it's 30 or above, or 27–29.9 with conditions like type 2 diabetes or high blood pressure, you may be eligible. Contact your GP to discuss options and get a referral to specialist weight loss services.
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.