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 Water Help With Weight Loss?
Yes, drinking enough water supports weight loss efforts, but water alone won't cause significant weight loss. Water can help you feel fuller, reduce appetite, and support metabolism—but sustainable weight loss typically requires a calorie deficit, physical activity, and sometimes medical support. If you're struggling with weight management in the UK, prescription medications like Mounjaro and Wegovy are available for eligible adults alongside lifestyle changes. This guide explains how water fits into your weight management strategy and what other options are available through the NHS and 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.
How Water Supports Weight Loss in the UK
Water plays a supportive role in weight management uk by helping regulate appetite and supporting metabolic function. Drinking water before meals may reduce overall food intake, as thirst is sometimes mistaken for hunger. Additionally, water has zero calories and helps your body process nutrients efficiently.
- Drinking 2–3 litres daily supports hydration and may reduce unnecessary snacking
- Water helps your body maintain muscle mass during weight loss
- Staying hydrated improves energy levels, supporting physical activity
- Water-rich foods (vegetables, fruits) enhance fullness without excess calories
However, water is most effective as part of a broader approach. The NHS weight loss guidance emphasises that sustainable lose weight uk requires a calorie deficit of approximately 500 kcal per day, combined with increased physical activity. For many people, this lifestyle foundation is enough. For others—particularly those with a BMI of 30 or above—prescription weight loss medication alongside lifestyle changes may be recommended.
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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 Loss Options Available in the UK
For adults who find lifestyle changes alone insufficient, the UK offers several prescription weight loss uk options through NHS specialist services or private prescribing. Mounjaro (tirzepatide) and Wegovy (semaglutide) are glp-1 weight loss injections that work alongside diet and exercise to reduce appetite and support weight management. Clinical trials showed that eligible adults using these weight loss injections uk lost an average of 15–21% of body weight, though individual results vary significantly.
Eligibility is determined by BMI, health conditions, and individual circumstances. Calculate your BMI using our free BMI calculator above to see if you might be eligible. If your BMI is 30 or above, or 27–29.9 with weight-related health conditions, discuss weight loss medication nhs options with your GP. Your GP can refer you to specialist tier 3 services, or you can explore private prescribing through a UK-licensed online prescriber following a clinical assessment.
- 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.
How much water should I drink daily for weight loss?
There is no specific "weight loss" amount, but the NHS recommends 6–8 cups (approximately 1.5–2 litres) of fluid daily for general health. Some evidence suggests drinking water before meals may support modest appetite reduction, but consistency with overall calorie intake matters more than water volume alone.
Can I lose weight by drinking water instead of other drinks?
Replacing sugary drinks with water is beneficial—a can of fizzy drink contains approximately 140 kcal, so this swap supports a calorie deficit. However, weight loss requires overall calorie reduction alongside physical activity. Water supports this process but doesn't create weight loss on its own.
What if water and lifestyle changes aren't enough for weight loss?
If you've followed a calorie-controlled diet and increased activity without sufficient results, prescription weight loss medication may help. Medications like Mounjaro and Wegovy are available in the UK for eligible adults with a BMI of 30 or above (or 27–29.9 with weight-related health conditions). Your GP can assess your eligibility and discuss options.
How do prescription weight loss injections work alongside diet?
Medications like Wegovy and Mounjaro are GLP-1 receptor agonists that reduce appetite and help you feel fuller after smaller meals. They work best alongside a reduced-calorie diet and increased physical activity—they support your efforts, not replace them. Track your progress using our free progress tracker.
How do I find out if I'm eligible for weight loss medication on the NHS?
Calculate your BMI using our free BMI calculator on this page. If your BMI is 30 or above, or 27–29.9 with conditions like type 2 diabetes or high blood pressure, speak to your GP. They can refer you to a specialist weight management service (tier 3). NHS availability varies by region, but specialist services can prescribe medications like Mounjaro if appropriate for you.
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.