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 Much Water Should I Drink for Weight Loss?
Water plays an important role in weight loss, but there's no single "clinically supported amount" that works for everyone. The amount of water you should drink depends on your age, activity level, climate, and overall health. Most UK health guidelines recommend drinking around 6–8 glasses (1.2–1.5 litres) of water daily as a baseline, though individual needs vary considerably. Proper hydration supports metabolism, helps you feel fuller, and can reduce the likelihood of mistaking thirst for hunger. This guide explains the science behind water and weight loss, and helps you work out your personal hydration needs.
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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.
Daily Water Intake Recommendations for Weight Loss
General guideline: The NHS suggests drinking about 6–8 glasses of water daily (approximately 1.2–1.5 litres). This is a baseline for most adults in a temperate UK climate.
Individual calculation method: A practical approach is to drink roughly 30–35 ml of water per kg of your body weight. For example, if you weigh 70kg, aim for 2.1–2.5 litres daily.
Activity adjustment: If you exercise regularly or have an active job, add 400–800 ml (0.5–1 litre) to your daily intake to compensate for fluid loss through sweat.
- Climate matters — hot weather or heated indoor environments increase fluid loss
- Pregnancy and breastfeeding increase water needs — consult your GP for personalised guidance
- Certain medical conditions (diabetes, kidney disease) may require adjusted intake — always check with your healthcare provider
Use our free BMI calculator to assess your current weight status, then adjust your hydration plan based on your activity level and personal goals.
Clinically BackedWeight Loss
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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.
How Water Supports Weight Loss and Healthy Weight
Water supports weight loss through several mechanisms. It has zero calories, so replacing sugary drinks with water automatically reduces energy intake. Drinking water before meals may increase satiety, leading to smaller portion sizes. Proper hydration also optimises metabolic function — even mild dehydration can slow metabolic rate by 3–5%.
When establishing your healthy weight range, remember that hydration is just one factor. Your ideal weight depends on your height, muscle mass, and overall health — not just water intake. Our weight converter helps you understand your current weight in both metric and imperial measurements, making it easier to track progress alongside better hydration habits. Combine consistent water intake with a balanced diet and physical activity for sustainable results.
- 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.
Does drinking more water automatically help you lose weight?
Water alone won't cause weight loss, but it supports the conditions that make weight loss easier. Proper hydration improves metabolism, reduces confusion between thirst and hunger, and helps you feel fuller. Weight loss requires a calorie deficit combined with healthy habits — water is a helpful tool, not a solution on its own.
Is it possible to drink too much water?
Yes, although it's rare. Drinking excessive water (several litres in a short period) can cause hyponatraemia (dangerously low sodium levels). Stick to gradual, consistent intake spread throughout the day. If you have kidney or heart conditions, consult your GP about safe limits.
Does water temperature affect weight loss?
Cold water slightly increases calorie burn as your body warms it, but the effect is minimal (around 4–8 kcal per litre). Warm water is equally hydrating. The more important factor is consistent daily intake. Choose whichever temperature encourages you to drink regularly.
Should I count tea, coffee, and other drinks towards my water intake?
Partially. Unsweetened tea and coffee contribute to daily fluid intake, though caffeine is a mild diuretic. Sugary drinks, cordials, and alcohol don't count — they add calories without the hydration benefit. Stick to water, plain tea, and black coffee as your primary sources.
How do I know if I'm drinking enough water?
Check your urine colour — pale yellow suggests adequate hydration; dark yellow suggests dehydration. Thirst is also a good indicator, though it lags slightly behind actual need. During weight loss, monitor energy levels and skin condition as well — both improve with proper hydration.
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.