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
Fruit Smoothies And Weight Loss: UK Prescription Options
Fruit smoothies can be part of a healthy diet, but many commercial smoothies are high in natural sugars and calories. If you're struggling with weight management in the UK, prescription medications like Mounjaro and Wegovy offer evidence-based support for eligible adults. This guide covers UK-licensed weight loss options, NHS eligibility criteria, and how to explore whether prescription treatment might help alongside diet and lifestyle changes. Our free GLP-1 weight loss calculator can help you understand potential outcomes if you're considering medication.
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 Medications
Three prescription-only medications are licensed in the UK for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, given as a once-weekly injection. Clinical trials showed participants lost an average of 15–21% of body weight over 72 weeks alongside diet and exercise.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, also a once-weekly injection. STEP trial data showed average weight loss of approximately 15% body weight at the maximum dose.
- Saxenda (liraglutide) — a GLP-1 injection given once daily, with similar average weight loss results to Wegovy.
All three work by regulating appetite hormones, slowing gastric emptying, and supporting you to feel fuller on smaller portions. Individual results vary significantly. These medications are prescribed only after clinical assessment and are used alongside reduced-calorie diet and increased physical activity — not as a replacement for lifestyle changes.
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 in the UK
NHS access: Prescription weight loss medications are available through specialist tier 3 or tier 4 weight management services. You'll typically need a referral from your GP, and eligibility criteria include a BMI of 30 or above (or 27+ with weight-related health conditions like type 2 diabetes or hypertension). However, NHS waiting lists vary significantly by region, and availability is not universal.
Private access: Prescription weight loss medications are available through GPhC-registered online pharmacies following an online clinical assessment with a UK-licensed prescriber. This route doesn't require NHS referral. Use our free BMI calculator to check where you sit on the NHS scale, then speak with your GP or explore private options if eligible. Your prescriber will assess which medication is appropriate based on your individual health profile.
- 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.
Can fruit smoothies help with weight loss?
Homemade smoothies with whole fruit, protein powder, and unsweetened liquid can be low-calorie and filling. However, shop-bought smoothies often contain added sugars and are high in calories. If you enjoy smoothies, make them at home with controlled portions. For more significant weight loss, prescription medication combined with structured diet changes may be more effective than diet alone.
Who is eligible for Mounjaro or Wegovy on the NHS?
NHS eligibility typically requires a 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. South Asian, Chinese, Black African, and Black Caribbean adults may have lower BMI thresholds (from 27.5). Your GP can refer you to a specialist weight management service to assess eligibility.
How much weight can I expect to lose with prescription medication?
Clinical trials show average weight loss of 15–21% of body weight over 72 weeks with Mounjaro, and around 15% with Wegovy. However, individual results vary significantly. Weight loss depends on your starting weight, adherence to medication, diet changes, and physical activity. Your prescriber can give personalised projections.
What's the difference between Mounjaro and Wegovy?
Mounjaro (tirzepatide) is a dual GIP and GLP-1 agonist, while Wegovy (semaglutide) is a GLP-1 agonist only. Clinical trial data suggests slightly higher average weight loss with Mounjaro, but both are effective. Your prescriber will assess which is more suitable for you based on your health profile, medical history, and other medications.
How do I find out if I'm eligible for weight loss medication?
Start by calculating your BMI using our free BMI calculator on this page. If your BMI is 30 or above (or 27+ with health conditions), speak with your GP about referral to a specialist weight management service. Alternatively, you can seek a private online consultation with a UK-licensed prescriber, who will assess your eligibility following a clinical 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.