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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Best Vegan Meal Replacement Shakes for Weight Loss in the UK
Vegan meal replacement shakes can be a convenient part of a weight loss plan, but for many UK adults, prescription weight management options may offer more significant support. While meal replacements help reduce calorie intake, they work best alongside lifestyle changes. If you have a BMI of 30 or above, or 27 or above with weight-related health conditions, you may be eligible for prescription weight loss medication through the NHS or private routes. This guide covers both dietary approaches and UK-licensed prescription options to help you understand the full range of weight management support available.
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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 Options Available in the UK
If dietary changes alone haven't delivered the results you need, prescription weight loss medication may be appropriate for you. The UK has three main GLP-1 medications licensed for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 agonist administered once weekly. Clinical trials showed users lost an average of 15–21% of body weight alongside a reduced-calorie diet and increased physical activity.
- Wegovy (semaglutide) — a GLP-1 agonist also given once weekly. Evidence suggests average weight loss of around 15% body weight in clinical trials.
- Saxenda (liraglutide) — a daily GLP-1 injection. All three are prescription-only and require a clinical assessment to determine eligibility.
Try our GLP-1 weight loss calculator to see how prescription weight loss medication might support your goals, and check your BMI using our free calculator to understand your starting point.
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're Eligible
NHS access: Ask your GP for referral to a tier 3 specialist weight management service. Eligibility typically requires BMI ≥30, or ≥27 with weight-related conditions like type 2 diabetes, high blood pressure, or sleep apnoea. NHS availability varies by region—waiting lists can be lengthy.
Private access: UK-licensed online prescribers offer assessments and prescriptions without NHS referral. A clinical consultation assesses your health and determines suitability. Costs range from approximately £129–£320 per month depending on dose.
Your first step is speaking with your GP about your weight management goals. They can assess whether prescription medication is appropriate and either refer you to NHS services or advise on private options. Individual results vary significantly.
- 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 vegan meal replacement shakes alone help me lose weight?
Vegan meal replacements can support weight loss by reducing calorie intake, but they work best combined with a balanced diet, physical activity, and behavioural changes. For significant, sustainable weight loss, most people benefit from a comprehensive approach. If you've struggled with meal replacements alone, prescription medication alongside lifestyle changes may be worth discussing with your GP.
Am I eligible for prescription weight loss medication on the NHS?
You may be eligible if you have a BMI of 30 or above, or 27 or above with weight-related health conditions such as type 2 diabetes, high blood pressure, or obstructive sleep apnoea. Eligibility varies by region and NHS specialist service availability. Contact your GP to discuss referral to a tier 3 weight management service.
What is 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 trials showed Mounjaro users lost an average of 15–21% body weight, compared to around 15% with Wegovy. Both are once-weekly injections. Individual results vary, and your prescriber will assess which is most suitable for you.
How quickly can I expect weight loss with prescription medication?
Prescription weight loss injections typically take 4–12 weeks to show noticeable effects. Weight loss continues gradually over months. The NHS recommends losing 0.5–1 kg per week for sustainable results. Medication works best alongside a reduced-calorie diet and increased physical activity. Individual results vary significantly.
How do I start the process of accessing prescription weight loss medication?
Start by speaking with your GP about your weight management goals and health concerns. They can refer you to an NHS specialist weight management service (tier 3) or advise on private prescribing options. A licensed prescriber will assess your medical history, current medications, and health conditions before determining suitability. Use our free BMI calculator to understand your starting point before your appointment.
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.