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 Aid In Weight Loss?
Water doesn't directly cause weight loss, but staying hydrated plays an important supporting role in any weight management UK programme. Drinking enough water can help reduce hunger signals, support metabolism, and prevent overeating — making it easier to maintain a calorie deficit. The NHS recommends drinking around 6–8 glasses (approximately 1.5 litres) of water daily for adults. When combined with balanced nutrition and physical activity, proper hydration becomes a practical foundation for sustainable weight loss.
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.
How Water Supports Weight Management
Water and appetite control: Drinking water before meals can help you feel fuller, potentially reducing the amount you eat at each sitting. The brain sometimes misinterprets thirst as hunger, so staying hydrated helps distinguish between genuine hunger and dehydration.
Metabolism and calorie burn: Research suggests that drinking water temporarily increases your metabolic rate — a small effect called thermogenesis. Cold water may have a slightly larger effect than room temperature water, as your body uses energy to warm it.
Replacing high-calorie drinks: Swapping sugary soft drinks, squashes, and alcoholic beverages for water removes hundreds of empty calories from your daily intake — one of the simplest ways to create a calorie deficit without changing meals.
- Aim for pale urine colour as a hydration marker
- Drink water throughout the day, not just at mealtimes
- Add lemon or cucumber for flavour without calories
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.
Water as Part of a Complete Weight Loss Plan
Water alone won't create sustained weight loss, but it's an essential component of nhs weight loss guidance. For meaningful, sustainable results, the NHS recommends combining hydration with a reduced-calorie diet and regular physical activity. Use our free BMI calculator above to check your current status, and if you're considering prescription weight loss medication as part of your journey, our GLP-1 weight loss calculator can help you explore what results might look like.
If you have a BMI above 30, or above 27 with weight-related health conditions, your GP can discuss options including lifestyle changes, structured weight loss programmes, or prescription medications like weight loss injections uk available through the NHS or private prescribing.
- 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 for weight loss?
The NHS recommends 6–8 glasses (1.5 litres) of water daily for general health. For weight loss support, consistency matters more than a specific amount — drink water regularly throughout the day, particularly before meals. Individual needs vary based on activity level and climate. Aim for pale urine as a hydration marker.
Can drinking water alone help me lose weight?
No. Water supports weight loss but doesn't cause it on its own. Sustainable weight loss requires a calorie deficit, achieved through reduced-calorie diet and increased physical activity. Water helps by reducing hunger, supporting metabolism, and replacing high-calorie drinks — but it's part of the complete picture, not a solution by itself.
Is cold water better than room temperature water for weight loss?
Cold water may have a marginally larger effect on metabolism than room temperature water, as your body uses energy to warm it. The difference is small — perhaps 10–20 extra calories per litre. The most important factor is drinking enough water consistently, regardless of temperature.
Can water help with appetite control when taking weight loss medication?
Yes. If you're prescribed prescription weight loss medication like GLP-1 injections, staying well hydrated supports overall health and can help manage side effects like nausea. Water also supports the appetite-reducing effects of these medications, helping you stick to reduced-calorie eating more easily.
Does drinking water before bed affect weight loss?
Drinking water before bed doesn't directly affect weight loss, but staying hydrated throughout the day — including in the evening — supports your metabolism and overall health. Excessive water close to bedtime may disturb sleep, so balance hydration with sleep quality. Consistent daily hydration matters more than timing.
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.