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 is often promoted as a weight loss tool, but what does the evidence actually show? Water itself contains no calories and plays an important role in metabolism and appetite regulation. However, water alone won't cause weight loss — sustainable weight loss requires a calorie deficit through diet and physical activity. That said, staying hydrated is an essential part of any effective weight management strategy and can support your overall health goals when combined with other evidence-based approaches.
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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
Water can play a useful supporting role in weight management, though it's not a standalone solution. Drinking water before meals may help you feel fuller, potentially reducing the amount you eat at that meal. Studies suggest this effect is modest but real — particularly important for nhs weight loss programmes that emphasise sustainable behaviour change.
- Water boosts metabolism very slightly — the body uses a small amount of energy to digest and absorb water, known as thermogenesis
- Staying hydrated supports kidney and liver function, which are important for metabolic health
- Replacing sugary drinks with water automatically reduces calorie intake — a simple swap that contributes to weight management uk approaches
- Dehydration can sometimes be confused with hunger, leading to unnecessary eating
However, these benefits are small compared to the impact of overall calorie intake and physical activity. Water is most effective as part of a broader weight loss strategy, not as a weight loss tool on its own.
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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.
Water and Weight Loss Medication
If you're taking prescription weight loss medication as part of lose weight uk efforts — such as GLP-1 injections like Mounjaro or Wegovy — staying well hydrated becomes even more important. These medications can cause side effects including nausea and constipation, and adequate water intake helps minimise discomfort.
How much water should you drink? The NHS recommends about 6–8 glasses (1.2 litres) of water daily, though individual needs vary based on activity level, climate, and overall health. If you're experiencing side effects from weight loss medication, your prescriber may recommend increasing intake further. Use our free GLP-1 weight loss calculator to explore how prescription medication fits into your weight management plan alongside lifestyle changes.
- 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.
Will drinking more water alone help me lose weight?
No, water alone won't cause weight loss. However, it supports weight management when combined with a calorie-controlled diet and increased physical activity. Water has no calories but can help you feel fuller at meals, reducing overall intake. The key to weight loss is maintaining a calorie deficit — water is a helpful tool, not a substitute for dietary changes.
How much water should I drink daily for weight loss?
The NHS recommends about 6–8 glasses (1.2 litres) of water daily for general health. For weight loss purposes, this amount is usually sufficient. Drinking a glass before meals may help with appetite control, but there's no evidence that drinking excessive amounts accelerates weight loss. Individual needs vary based on activity level and climate.
Does drinking water speed up metabolism?
Water does cause a very slight increase in metabolic rate — a phenomenon called thermogenesis. However, this effect is minimal (around 2–3% of daily calories) and alone won't result in meaningful weight loss. The effect is most noticeable when water replaces high-calorie drinks, automatically reducing overall calorie intake.
Can water help if I'm taking weight loss injections?
Yes, staying hydrated is particularly important if you're taking prescription weight loss medication like Mounjaro or Wegovy. These medications can cause nausea and constipation, and adequate hydration helps manage these side effects. Your prescriber may recommend specific intake levels based on your individual response to treatment.
What's the difference between water intake and actual weight loss?
Water intake and weight loss are separate. Drinking more water won't reduce body fat, but it supports the processes needed for sustainable weight loss — including appetite regulation, metabolism, and kidney function. Effective weight loss requires a calorie deficit through diet and exercise; water is a supporting factor, not a primary driver.
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.