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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Drinks for Weight Loss — UK Options and Prescription Support
While weight loss drinks can support a reduced-calorie diet, the most effective approach combines healthy habits with professional support. In the UK, prescription medications like Mounjaro and Wegovy have shown strong clinical evidence for weight management. If you're struggling with weight loss through diet and exercise alone, your GP can assess whether prescription options are suitable for you. This guide explores both dietary approaches and NHS-approved medication that may help with weight management 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.
Prescription Weight Loss Medication Available in the UK
Three prescription-only weight management medications are licensed in the UK for eligible adults: Mounjaro (tirzepatide), Wegovy (semaglutide), and Saxenda (liraglutide). These are not supplements — they are prescription medicines that work alongside reduced-calorie diets and increased physical activity.
Mounjaro is a dual GIP and GLP-1 receptor agonist; clinical trials showed participants lost an average of 15–21% of their body weight over 72 weeks. Wegovy is a GLP-1 receptor agonist; evidence suggests average weight loss of approximately 15% in clinical trials. Both are once-weekly injections. Eligibility includes adults with BMI ≥30 or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea). Your GP or a licensed prescriber will assess whether you qualify.
- All three are prescription-only medicines requiring clinical assessment
- Results vary between individuals — not assured
- Usually combined with dietary and lifestyle changes
- Available through NHS specialist services or private prescribing in the UK
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 Get Started
NHS access: Specialist tier 3 weight management services prescribe these medications following referral from your GP. However, availability varies significantly by region and waiting times can be lengthy. Contact your GP to ask about your local NHS weight management pathway.
Private access: UK-licensed prescribers offer online assessments; if approved, medications are dispensed by GPhC-registered pharmacies. This route doesn't require NHS referral but involves private cost. Either route requires a genuine clinical assessment — not a quick online form.
Use our free BMI calculator on this page to check your current BMI, which helps determine eligibility. Our GLP-1 weight loss calculator can help estimate potential results at different doses if you qualify. Track your progress with our free progress tracker to monitor weight 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 weight loss drinks effective on their own?
Weight loss drinks (like green tea, water-based recipes, or low-calorie beverages) can support a reduced-calorie diet but are not sufficient alone for significant weight loss. Sustainable weight management requires a calorie deficit, usually 500 kcal/day, combined with lifestyle changes. Prescription medications like Mounjaro or Wegovy have stronger clinical evidence when combined with dietary changes.
Who is eligible for prescription weight loss medication in the UK?
Adults with BMI ≥30 kg/m², or BMI 27–29.9 with weight-related health conditions (type 2 diabetes, high blood pressure, cardiovascular disease, or sleep apnoea) may be eligible. Lower thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP or prescriber will assess your individual eligibility following consultation.
How much weight can I expect to lose with Mounjaro or Wegovy?
Clinical trials showed average weight loss of 15–21% for Mounjaro and approximately 15% for Wegovy, though individual results vary significantly. Weight loss depends on dose, adherence, dietary changes, and physical activity. Your prescriber will discuss realistic expectations based on your circumstances — there is no assured outcome.
What's the difference between NHS and private weight loss medication access in the UK?
NHS access requires GP referral to specialist tier 3 services; availability and waiting times vary by region. Private access uses online prescribers and GPhC-registered pharmacies without NHS referral but involves private cost. Both require genuine clinical assessment; neither offers instant access without proper evaluation.
Can I get prescription weight loss medication from my GP directly?
Most GPs cannot prescribe weight loss medications directly; prescription usually comes through specialist tier 3 NHS weight management services following referral. Some GPs may signpost private prescribing options. Ask your GP about your local pathway or whether they recommend private assessment if NHS waiting times are lengthy.
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.