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
Weight Loss By Water Intake — Does It Really Work?
Drinking more water can support weight loss, but it's not a standalone solution. Water helps with feelings of fullness, can boost metabolism slightly, and replaces high-calorie drinks — all valuable for weight management in the UK. However, sustainable weight loss requires a calorie deficit, increased physical activity, and sometimes medical support. Understanding how water fits into your overall weight loss strategy is key to seeing lasting results.
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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
Water plays several roles in supporting healthy weight management. Drinking water before meals can help you feel fuller, leading to eating smaller portions and reducing overall calorie intake. Studies suggest drinking 500ml of water 30 minutes before eating may help reduce calorie consumption by up to 13% in some cases.
Replacing sugary drinks with water is one of the most effective changes you can make. A single can of fizzy drink contains around 140 calories and 35g of sugar — switching to water eliminates this without any nutritional loss. Over a year, this single change could result in weight loss of several kilograms.
Water also has a minor effect on metabolic rate. Drinking cold water requires your body to use energy to warm it, burning an extra 20–30 calories per litre. While modest, this adds up over time when combined with other weight loss strategies.
The NHS emphasises that proper hydration supports overall health — including better energy levels for exercise and improved digestion. Most UK adults need 6–8 glasses (1.2–1.5 litres) of water daily, though individual needs vary.
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 Intake Alone Isn't Enough for Weight Loss
While water is beneficial, it cannot create the calorie deficit needed for weight loss on its own. To lose weight sustainably at the NHS-recommended rate of 0.5–1 kg per week, you need to consume fewer calories than you burn. This requires dietary changes, physical activity, and often behaviour modification.
Some people wonder if excessive water intake alone can lead to weight loss. The answer is no — your body excretes excess water through urine. Drinking 3–4 litres daily without changing diet or activity won't produce weight loss, though proper hydration remains important for health.
For many people, combining water intake with other evidence-based approaches — like reduced-calorie eating, regular movement, and sometimes prescription weight loss medication — delivers better results. If you're struggling with weight management, check your BMI using our free BMI calculator above, and speak with your GP about support options including NHS weight management services or prescription treatments like GLP-1 injections.
- 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 to support weight loss?
The NHS recommends 6–8 glasses (1.2–1.5 litres) of water daily for most adults. Some research suggests drinking 3 litres may enhance satiety, but individual needs vary based on activity level, climate, and health. Drink enough so your urine is light coloured — a simple way to check hydration status. More water doesn't automatically mean more weight loss.
Can drinking water before meals really help me eat less?
Yes, some evidence supports this. Drinking 500ml of water 30 minutes before eating may help you feel fuller and consume fewer calories. However, this is most effective as part of a broader weight loss plan including diet changes and physical activity. It's not a standalone weight loss method.
Is drinking water better than diet drinks for weight loss?
Yes, plain water is the best choice. Diet drinks are calorie-free but contain artificial sweeteners, which some research links to altered appetite regulation. Water has zero calories, no sweeteners, and supports overall health. Replacing regular fizzy drinks with water is one of the easiest dietary changes to support weight loss.
Can water intake alone help me lose weight?
No. Water supports weight loss as part of a comprehensive approach, but cannot create the calorie deficit needed on its own. Sustainable weight loss requires eating fewer calories than you burn through diet and activity. Water helps by increasing fullness and replacing high-calorie drinks, but isn't a standalone solution.
Will drinking more water boost my metabolism significantly?
Drinking cold water has a very modest effect on metabolism — burning approximately 20–30 extra calories per litre. While this is real, it's small compared to the 500+ calorie deficit needed for 0.5 kg weekly weight loss. Water's main benefit for weight loss is supporting feelings of fullness and replacing calorie-dense drinks.
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.