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
Detox Drinks For Weight Loss — And What Actually Works In The UK
Homemade detox drinks are popular for weight management, but evidence for their effectiveness is limited. While staying hydrated is important, sustainable weight loss in the UK typically requires a calorie deficit combined with lifestyle changes. For eligible adults, prescription weight loss medication offers evidence-based alternatives. Our free GLP-1 weight loss calculator can help you explore potential outcomes if you qualify for treatment. This guide covers what the evidence actually shows and what prescription options are available through the NHS and privately.
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 Prescription Weight Loss Options — Mounjaro, Wegovy, And Saxenda
If you're looking for effective weight management in the UK, prescription medications offer clinically proven results. Three main options are licensed for weight loss:
- Mounjaro (tirzepatide) — A dual GIP and GLP-1 injection. Clinical trials showed participants lost an average of 15–21% of body weight over 72 weeks alongside diet and exercise.
- Wegovy (semaglutide) — A once-weekly GLP-1 injection. STEP trial data showed average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — A once-daily GLP-1 injection. Available on the NHS and privately for eligible adults.
All three are prescription-only medicines requiring clinical assessment. Unlike detox drinks, these medications work by reducing appetite, supporting feeling fuller, and helping regulate how your body processes food. Use our free BMI calculator above to check if you might be eligible based on UK health thresholds.
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.
NHS Vs Private Access — How To Find Out If You Qualify
NHS access: Referral to a tier 3 specialist weight management service through your GP. Availability varies significantly by region, and waiting lists can be lengthy. Your GP can discuss whether you meet the criteria: BMI of 30 or above, or 27–29.9 with weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea.
Private access: GPhC-registered online prescribers offer assessment and prescription without NHS referral. Available to eligible adults with costs typically from £129–£320 monthly depending on dose and provider.
The best first step is speaking to your GP about NHS weight loss options and your individual circumstances. They can assess whether prescription treatment is right 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.
Are homemade detox drinks effective for weight loss?
Homemade detox drinks have limited scientific evidence for weight loss. Staying hydrated is beneficial, but drinks alone won't create the calorie deficit needed for sustainable weight loss. Prescription medications combined with lifestyle changes are more effective for significant weight management.
What is the difference between Mounjaro and Wegovy for weight loss?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 medication with average weight loss of 15–21% in trials. Wegovy (semaglutide) is a GLP-1 only medication with average weight loss around 15%. Both are prescription-only and require clinical assessment. Your prescriber will determine which is suitable for you.
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 health conditions like diabetes or high blood pressure. South Asian, Chinese, Black African, and Black Caribbean adults have lower thresholds. Speak to your GP or a licensed prescriber for a personalised assessment.
Can I get weight loss medication through the NHS, or only privately?
Both options exist in the UK. NHS access is through specialist tier 3 weight management services (referral from GP required), though regional availability and waiting times vary. Private prescribers offer faster access without NHS referral. Your GP can advise on local NHS availability.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight with medications like Mounjaro and Wegovy over 72 weeks, alongside reduced-calorie diet and increased physical activity. Individual results vary significantly. A prescriber will discuss realistic expectations during your assessment.
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.