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
How Does Drinking Water Help With Weight Loss?
Drinking water plays an important role in weight management and supporting your body's natural processes. Water has no calories, helps regulate appetite, boosts metabolism, and improves how your body processes food and fat. Whether you're managing your weight through lifestyle changes, prescription weight loss medication, or a combination of approaches, staying properly hydrated is a practical step that supports your efforts. Understanding how water contributes to weight loss helps you make informed choices about your overall health strategy.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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.
The Science Behind Water and Weight Loss
Water supports weight loss through several evidence-based mechanisms. Drinking water before meals helps you feel fuller, which may reduce the amount you eat. When you drink water, your stomach volume increases, signalling satiety to your brain. This is particularly helpful if you're following a reduced-calorie diet for weight management in the UK.
Water also plays a crucial role in metabolism. Your body burns calories during digestion, a process called thermogenesis — and drinking water temporarily increases this effect. Studies suggest that drinking 500ml of water can increase your metabolic rate by up to 30% for around 30 minutes.
- Water has zero calories, unlike sugary drinks which contribute significant energy intake
- Proper hydration supports kidney and liver function — both essential for processing and eliminating fat
- Dehydration can trigger false hunger signals, leading to unnecessary snacking
- Cold water may increase calorie burn as your body works to warm it to body temperature
If you're using prescription weight loss medication like Mounjaro or Wegovy as part of a wider weight management strategy, staying hydrated is equally important for your overall health and helps reduce gastrointestinal side effects some people experience.
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.
Practical Hydration Tips for Weight Loss
Aim to drink between 6 and 8 glasses (1.5 to 2 litres) of water daily — though individual needs vary based on activity level, climate, and health status. Drink water before meals to promote satiety; aim for a glass 20–30 minutes before eating. Replace sugary drinks, fruit juices, and high-calorie beverages with water to create a calorie deficit without reducing food volume.
Track your weight loss progress using our free progress tracker to see how lifestyle changes, including hydration, support your goals. Calculate your personal BMI using our free BMI calculator to monitor your weight management journey against NHS healthy weight guidelines. If you're considering prescription weight loss options, our GLP-1 weight loss calculator can help you understand potential outcomes when combined with healthy habits like proper hydration.
- 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 to 8 glasses of water daily (about 1.5 to 2 litres). Individual needs vary based on activity, climate, and health. Drinking more water during exercise or hot weather is important. Always consult your GP if you have kidney problems or conditions affecting fluid intake.
Can drinking water alone help me lose weight?
Water supports weight loss as part of a comprehensive approach, but it cannot replace a calorie deficit or healthy lifestyle. Weight loss requires reduced calorie intake and increased physical activity. Prescription weight loss medication, when appropriate, works alongside these habits — not instead of them.
Does drinking water before meals really help reduce appetite?
Yes, evidence suggests drinking water before meals can increase feelings of fullness and reduce food intake. Drinking 500ml of water 20–30 minutes before a meal may help you eat less. This effect is modest but meaningful as part of overall weight management strategy.
Can I drink too much water while trying to lose weight?
Yes — excessive water intake can be harmful, potentially causing hyponatraemia (dangerously low sodium levels). Aim for 2–3 litres daily unless your GP advises differently. If you have heart, kidney, or liver conditions, discuss safe hydration levels with your healthcare provider.
Does water help if I'm taking weight loss injections like Mounjaro or Wegovy?
Yes, staying hydrated supports overall health and can reduce gastrointestinal side effects some people experience with GLP-1 medications. Water has no calories and complements prescription weight loss treatment. Always follow your prescriber's guidance on hydration alongside medication use.
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.