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
Warm Water and Weight Loss — What Works in the UK
Drinking warm water is often suggested as a simple weight loss aid, but evidence for its direct impact is modest. While staying hydrated supports overall health and may help with appetite control, the most effective approach to weight management uk combines lifestyle changes with clinical support. For adults struggling with excess weight, prescription weight loss medication is now available through the NHS and private prescribing in the UK, offering evidence-based options alongside diet and hydration strategies.
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.
UK-Licensed Weight Loss Medications for Eligible Adults
If you have a BMI of 30 or above, or a BMI of 27–29.9 with weight-related health conditions, you may be eligible for prescription weight loss treatment in the UK. Three medications are currently licensed for weight management:
- Mounjaro (tirzepatide) — a once-weekly injection that works on two appetite pathways; clinical trials showed an average weight loss of 15–21% body weight alongside diet and activity changes
- Wegovy (semaglutide) — a once-weekly GLP-1 injection; trial data showed approximately 15% average body weight loss
- Saxenda (liraglutide) — a daily GLP-1 injection; offers similar efficacy to other GLP-1 options
These work best when combined with reduced-calorie diet and increased physical activity — including staying hydrated with warm water and other healthy habits. Individual results vary significantly, and a prescriber will assess eligibility based on your personal health.
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.
Getting Started with Weight Loss Support in the UK
There are two main routes to access prescription weight loss medication in the UK:
- NHS route: Speak to your GP about referral to a specialist tier 3 weight management service. Availability and waiting times vary by region.
- Private route: Prescription weight loss options are available through online UK prescribers following a clinical assessment, without NHS referral.
Start by calculating your BMI using our free BMI calculator to understand where you stand on NHS weight loss guidelines. Your GP can discuss whether you're eligible and which approach suits you best. Combined with hydration, balanced nutrition, and physical activity, prescription support can help you achieve 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 warm water actually help weight loss?
Warm water supports hydration, which aids appetite control and metabolism, but has no direct fat-burning effect. It's a helpful habit alongside other strategies, but prescription weight loss medication and lifestyle changes are more impactful for significant, sustained weight loss.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You may be eligible if your BMI is 30 or above, or 27–29.9 with weight-related conditions like diabetes or high blood pressure. A GP or licensed prescriber can assess your individual eligibility. Use our free BMI calculator to check your starting point.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 injection showing 15–21% average weight loss; Wegovy (semaglutide) is a GLP-1-only injection with approximately 15% average loss. Both are once-weekly. Individual response varies, and a prescriber chooses based on your health profile.
Can I get weight loss injections through the NHS in the UK?
Yes. NICE has approved tirzepatide and semaglutide for NHS specialist weight management services. Access is through tier 3 services, usually via GP referral. Availability and waiting times vary significantly by region — your GP can advise on local options.
How much weight can I expect to lose with prescription medication?
Clinical trials show average losses of 15–21% body weight with Mounjaro and around 15% with Wegovy, but results vary considerably between individuals. These medications work best alongside a reduced-calorie diet and increased activity. A prescriber will give you personalised expectations based on your health.
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.