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
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Detoxification Water For Weight Loss — What Works In The UK
Detoxification water is often promoted as a weight loss solution, but scientific evidence for its effectiveness is limited. If you're looking to lose weight in the UK, prescription medications like Mounjaro and Wegovy offer clinically proven support when combined with lifestyle changes. This guide explains what detoxification water is, why it's popular, and what evidence-based options are actually available through the NHS and private prescribing in the UK.
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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.
UK-Licensed Prescription Weight Management Options
If detoxification water hasn't delivered results, prescription weight management may be worth considering. In the UK, three medications are licensed specifically for weight loss: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
- Mounjaro — A dual GIP and GLP-1 receptor agonist. Clinical trials showed participants lost an average of 15–21% of body weight over 72 weeks, alongside reduced-calorie diet and increased physical activity.
- Wegovy — A GLP-1 receptor agonist with a maximum dose of 2.4 mg once weekly. Clinical evidence demonstrated approximately 15% average body weight loss in trials.
- Saxenda — A daily GLP-1 injection, typically used when once-weekly options are unsuitable.
All three are prescription-only medicines requiring a clinical assessment by a licensed UK prescriber to confirm eligibility.
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.
Eligibility And How To Access Weight Loss Treatment In The UK
You may be eligible for prescription weight loss medication if you have a BMI of 30 kg/m² or above, or a BMI of 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. Lower BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults due to increased health risks at lower weights.
In the UK, access is through NHS specialist weight management services (referral from your GP, often with waiting lists) or private online prescribing (requires assessment from a UK-licensed prescriber). Check your BMI using our free BMI calculator above, then speak with your GP about whether prescription options are suitable for you.
- 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 detoxification water actually help you lose weight?
Scientific evidence supporting detoxification water for weight loss is weak. While staying hydrated is important for health and can support weight management, specific "detox" claims are largely marketing-driven. Weight loss requires a sustained calorie deficit, regular physical activity, and dietary changes — water alone cannot achieve this without lifestyle modification.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro is a dual GIP and GLP-1 receptor agonist (maximum dose 15 mg weekly), whilst Wegovy is a GLP-1 agonist only (maximum 2.4 mg weekly). In clinical trials, Mounjaro showed slightly higher average weight loss (15–21% vs ~15%), but individual results vary significantly. Both require prescription and clinical assessment. Your GP or prescriber can advise which is more suitable.
Can I get prescription weight loss medication on the NHS?
Yes, prescription weight loss medications are available through NHS specialist tier 3 weight management services. However, access varies significantly by region and waiting lists can be lengthy. Your GP can refer you for assessment. Alternatively, private prescribing through UK-licensed prescribers is available without NHS referral, though this involves private costs.
What is the healthy weight loss rate recommended in the UK?
The NHS recommends losing no more than 0.5 to 1 kg (1–2 lbs) per week for sustainable results. This typically requires a calorie deficit of around 500 kcal per day. Faster weight loss increases the risk of muscle loss and nutrient deficiencies. Use our free progress tracker to monitor your weight loss journey at a healthy pace.
What should I do if detox water hasn't helped me lose weight?
If lifestyle changes alone aren't working, speak with your GP about your weight management concerns. They can assess whether prescription medication, referral to specialist services, or structured behaviour change programmes might help. Try our GLP-1 weight loss calculator to see projected outcomes if you become eligible for prescription support.
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.