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
Can Water Help Weight Loss?
Yes, drinking adequate water can support weight loss, but it's not a clinically supported solution. Water helps maintain metabolism, reduces appetite, and supports the body's natural fat-burning processes. However, sustainable weight loss requires a calorie deficit alongside increased physical activity. In the UK, the NHS recommends using our free BMI calculator to understand your starting point, then combining proper hydration with dietary changes and lifestyle modifications for effective weight management.
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 Loss
Water plays several important roles in weight management in the UK health context:
- Increases satiety: Drinking water before meals can make you feel fuller, reducing overall calorie intake. Studies suggest this effect is modest but measurable.
- Supports metabolism: Staying hydrated helps your body efficiently burn calories. Dehydration can slow metabolic rate by up to 3%.
- Replaces calorie-containing drinks: Swapping sugary drinks, alcohol, and high-calorie beverages for water creates a meaningful calorie deficit without dietary restriction.
- Aids digestion: Adequate water intake supports digestive function and nutrient absorption.
- Reduces water retention: Counterintuitively, drinking enough water prevents the body from retaining excess fluid, which can mask weight loss progress on the scales.
For sustainable weight loss, aim for 6–8 glasses of water daily, or approximately 1.5–2 litres. Individual needs vary based on activity level, climate, and body size.
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 Alone Isn't Enough
While hydration is important, water alone cannot create the calorie deficit needed for weight loss. The NHS emphasises that effective weight loss requires a combination of factors: reduced calorie intake, increased physical activity, and consistent lifestyle changes. For prescription weight loss in the UK, medications like GLP-1 injections work alongside dietary modification and exercise—not as replacements. Try our free GLP-1 weight loss calculator to explore how prescription weight loss support works. Water is a valuable supporting habit, but it must be part of a broader weight management strategy. If you're struggling to lose weight through diet and exercise alone, speak to your GP about whether structured support or medication might help.
- 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 (approximately 1.5–2 litres) of water daily for most adults. Needs vary based on activity level, climate, and individual factors. Drinking water before meals may support satiety, but consistency with overall calorie intake matters more than total water volume alone.
Does drinking water increase metabolism?
Yes, water temporarily boosts metabolic rate through a process called thermogenesis. Drinking cold water may have a slightly greater effect than room-temperature water, but the increase is modest (around 3% at most). This small boost is most meaningful when combined with reduced-calorie diet and physical activity.
Can water help with weight loss without dieting?
No. Water supports weight loss but cannot create the calorie deficit needed for weight loss on its own. Sustainable weight loss requires reduced calorie intake and increased physical activity. Water is a helpful supporting habit, not a weight loss solution by itself.
Is tap water or bottled water better for weight loss?
Both tap and bottled water have identical hydration benefits for weight loss. Choose whichever you'll drink consistently. Tap water in the UK is safe, well-regulated, and cost-effective. Avoid adding sugars, flavourings, or high-calorie additives, as these eliminate water's weight management benefits.
Should I drink water if I'm taking weight loss medication like Mounjaro or Wegovy?
Yes, staying well-hydrated is important when taking any medication, including weight loss injections. GLP-1 medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) work alongside hydration, diet, and exercise. Always follow your prescriber's guidance on fluid intake, as some individuals experience nausea or changes in appetite that may affect hydration needs.
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.