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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Health Drinks for Weight Loss — What Works in the UK?
While commercial health drinks marketed for weight loss exist, the most effective weight management options available in the UK include prescription medications like Mounjaro and Wegovy. These GLP-1 weight loss injections are licensed by the MHRA and prescribed through NHS specialist services or private clinics. If you're considering weight management, understanding your BMI and eligibility for prescription options may be more beneficial than relying on drinks alone. This guide explains what's available to eligible UK adults and how to find out if prescription weight loss medication is right for you.
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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
For adults seeking clinical support with weight management in the UK, three prescription medications are licensed and available: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide).
Mounjaro is a once-weekly injection that works as a dual GIP and GLP-1 receptor agonist. In clinical trials, it helped participants lose an average of 15–21% of their body weight alongside a reduced-calorie diet and increased physical activity. Wegovy is also a once-weekly injection (GLP-1 agonist only), with average weight loss of around 15% in clinical trials. Saxenda is a daily injection option with slightly lower average weight loss.
All three are prescription-only medicines requiring a clinical assessment before dispensing. Individual results vary significantly. Eligibility typically requires a BMI of 30 or above, or 27 or above if you have weight-related health conditions such as type 2 diabetes, high blood pressure, or sleep apnoea. Use our free BMI calculator above to check your personal BMI and understand where you fall on the NHS weight categories.
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 — Finding Your Route
In the UK, prescription weight loss medication is available through two routes: NHS specialist services and private online clinics.
NHS access: Referral to a tier 3 specialist weight management service through your GP. NICE has approved tirzepatide and semaglutide for use within NHS services. However, availability varies significantly by region, and waiting lists can be lengthy in many areas.
Private access: Through GPhC-registered online pharmacies following an assessment by a UK-licensed prescriber. This route does not require an NHS referral and typically offers faster access, though at a cost.
Start by speaking with your GP about weight management support. They can assess your individual circumstances, discuss medication eligibility, and either refer you to NHS services or support your private options. Track your progress using our free progress tracker to monitor changes over time.
- 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 health drinks alone effective for weight loss?
Commercial health drinks can be part of a weight management approach, but they work best alongside a calorie deficit and increased physical activity. For significant, sustained weight loss, NHS guidelines recommend a combination of dietary changes, physical activity, and — where eligible — prescription medication if needed. Individual results vary based on lifestyle, genetics, and overall health.
How do I know if I'm eligible for Mounjaro or Wegovy on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27 or above with a weight-related health condition (such as type 2 diabetes, hypertension, or sleep apnoea). Eligibility is assessed individually by a GP or specialist. Use our BMI calculator above to check your BMI, then speak with your GP about your options.
What's the difference between Mounjaro and Wegovy?
Both are once-weekly injections, but Mounjaro (tirzepatide) uses a dual GIP and GLP-1 mechanism, whilst Wegovy (semaglutide) is GLP-1 only. Clinical trials showed Mounjaro achieved slightly higher average weight loss (15–21%) compared to Wegovy (around 15%), though results vary between individuals. Your prescriber will assess which is more suitable for you.
How quickly will I lose weight on prescription medication?
The NHS recommends losing 0.5–1 kg per week for sustainable results. Prescription weight loss medications work gradually — doses are increased over weeks, and weight loss typically becomes more noticeable after 8–12 weeks. However, individual results vary significantly. These medications work best alongside reduced-calorie diet and increased physical activity.
Can I get weight loss injections privately if the NHS waiting list is long?
Yes. Private online clinics in the UK can prescribe Mounjaro and Wegovy following an online clinical assessment by a UK-licensed prescriber. Private prescriptions are dispensed by GPhC-registered pharmacies. Costs vary by dose and provider. Always ensure any provider is GPhC-registered before using their service.
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.