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
Weight Loss Drinks and Prescription Medication — What Works in the UK
Weight loss drinks are often marketed as quick solutions, but evidence shows they're rarely effective alone. If you're looking for genuine weight management support in the UK, prescription medications alongside lifestyle changes offer a more clinically proven approach. This guide covers NHS and private options available to eligible adults, including how to find out if you qualify for prescription weight loss treatment.
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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 Loss Options
Three prescription medications are licensed in the UK for weight management: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are GLP-1 and GIP receptor agonist injections that work by regulating appetite and helping you feel fuller after smaller meals. Clinical trials show these medications support meaningful weight loss when combined with reduced-calorie diet and increased physical activity.
Eligibility criteria: Adults with a BMI of 30 or above, or 27–29.9 with weight-related health conditions (diabetes, high blood pressure, sleep apnoea) may qualify. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds apply. Prescription weight loss medication is not a substitute for lifestyle changes — it's a tool to support them. Use our free GLP-1 weight loss calculator to see projected outcomes at different doses, and our BMI calculator to check your current BMI category.
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.
How to Access Weight Loss Treatment in the UK
In the UK, you can access prescription weight loss medication through two routes. NHS specialist services: Refer yourself or ask your GP for a referral to your local tier 3 weight management service. NHS eligibility and waiting times vary significantly by region. Private prescribing: You can obtain a prescription through a UK-licensed online prescriber following an online clinical assessment — no NHS referral needed. Private costs range from approximately £129–£320 per month depending on dose and provider.
Your GP can advise which route is appropriate for you and assess whether prescription medication is suitable based on your health history. Weight loss is most successful when combining medication with dietary changes and physical activity.
- 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 weight loss drinks effective for losing weight?
Most commercial weight loss drinks have limited evidence for significant weight loss. Typical drink-based approaches provide calories or supplements but don't address appetite regulation or behaviour change — the key factors in sustainable weight loss. They may support hydration or reduce calorie intake modestly, but prescription medications have substantially stronger clinical evidence.
What's the difference between Mounjaro and Wegovy?
Both are prescription injections for weight management, but work differently. Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist alone. Clinical trials show Mounjaro may support slightly greater average weight loss (~20.9% at highest dose) versus Wegovy (~14.9%). Individual results vary significantly — your prescriber will assess which is most appropriate.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 14–21% of body weight over 68–72 weeks, alongside diet and exercise. However, individual results vary considerably — some people lose more, some less. Your GLP-1 weight loss calculator can help estimate potential outcomes at different doses based on your starting weight and health profile.
Do I need a GP referral to get prescription weight loss medication?
For NHS treatment, yes — ask your GP to refer you to your local specialist weight management service. For private prescribing, no referral is needed; you can access an online clinical assessment directly. Your GP can advise which route suits your situation and confirm you're medically suitable for treatment.
Can I get weight loss medication on the NHS?
Yes. NICE has approved prescription weight loss medications for use within NHS specialist tier 3 services. Access depends on your local ICB (Integrated Care Board) and referral criteria. Wait times vary from weeks to years depending on your area. Your GP can explain local availability and help you understand the referral process.
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.