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
Why Is Drinking Water Good For Weight Loss?
Drinking water is one of the simplest yet most effective tools for supporting weight loss. Water increases your metabolic rate, helps you feel fuller between meals, and supports your body's natural fat-burning processes. In the UK, hydration is recommended by the NHS as a key part of sustainable weight management. When combined with a balanced diet, regular physical activity, and — for eligible adults — prescription weight loss medication, water intake becomes an essential building block of your overall health strategy.
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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.
Prescription Weight Loss Options Available in the UK
For adults struggling with weight management, the UK offers several prescription weight loss medications available through NHS specialist services or private prescribing. These include:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, dosed from 2.5 mg to 15 mg once weekly. Clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, dosed up to 2.4 mg once weekly. In clinical trials, average weight loss was approximately 15% of body weight.
- Saxenda (liraglutide) — a daily GLP-1 injection dosed up to 3 mg per day, suitable for those who prefer daily dosing.
All three medications are prescription-only and require a clinical assessment to determine eligibility. You are eligible if you have a BMI of 30 or above, or BMI 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or cardiovascular disease. Individual results vary significantly, and medications work best alongside hydration, dietary changes, and increased physical activity.
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 vs Private Access and Next Steps
In the UK, prescription weight loss medication is available through two routes. The NHS route involves a referral from your GP to a specialist tier 3 weight management service; however, waiting lists vary significantly by region and can be lengthy. The private route offers faster access through GPhC-registered online pharmacies following a clinical assessment, though costs typically range from £129–£320 per month depending on dose.
If you are interested in exploring whether prescription weight loss treatment is right for you, start by speaking with your GP about your weight management goals. They can assess your individual health circumstances, discuss NHS options, or provide guidance on private services. Use our free BMI calculator to check your current BMI category, and our GLP-1 weight loss calculator to see projected weight loss outcomes at different medication doses. Remember: hydration, consistent physical activity, and balanced nutrition remain essential alongside any medication.
- 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?
The NHS recommends 6–8 glasses of fluid daily — approximately 1.5 litres. This includes water, tea, and other low-sugar drinks. Drinking water before meals may help you feel fuller and eat less, supporting a calorie deficit. Individual needs vary based on activity level and body size, so adjust accordingly.
Can water alone help me lose weight?
Water supports weight loss by boosting metabolism and reducing hunger, but cannot produce weight loss on its own. Sustainable weight loss requires a calorie deficit through diet and physical activity. For some adults, prescription weight loss medication like Mounjaro or Wegovy — alongside hydration and lifestyle changes — may be appropriate. Your GP can advise whether you are eligible.
Is it better to drink water before or after meals?
Drinking water before meals may help reduce overall calorie intake by promoting earlier fullness. Drinking water during and after meals supports digestion and hydration. The most important factor is consistent hydration throughout the day, not the precise timing. Aim for regular water intake rather than occasional large amounts.
What is the difference between GLP-1 medications like Wegovy and lifestyle changes?
Lifestyle changes — including hydration, diet, and exercise — are the foundation of weight management. GLP-1 medications like Wegovy and Mounjaro are prescription treatments that support appetite regulation and may enhance results when combined with lifestyle changes. They are available through NHS or private prescribing for eligible adults. A prescriber will assess whether medication is appropriate for you.
How do I check if I am eligible for prescription weight loss medication in the UK?
In the UK, you may be eligible if you have a BMI of 30 or above, or BMI 27–29.9 with weight-related conditions such as diabetes or high blood pressure. Use our free BMI calculator to check your current BMI, then speak with your GP about eligibility. They can discuss NHS specialist services or guide you toward private prescribing options. Individual assessment is required.
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.