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
Plant-Based Supplements for Weight Loss — What the Evidence Shows
Plant-based supplements are popular for weight management, but evidence for most is limited. While some herbal ingredients may support healthy weight loss alongside diet and exercise, prescription medications offer stronger clinical evidence for eligible UK adults. This guide explains what plant-based options claim to do, why prescription weight loss medication may be more effective, and how to find out if you're eligible through the NHS or private prescribing services.
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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 you're looking for evidence-based weight management in the UK, prescription medications offer more robust clinical support than supplements. Three medications are currently licensed for weight management:
- Mounjaro (tirzepatide) — a dual GIP and GLP-1 receptor agonist, injected once weekly. Clinical trials showed average weight loss of 15–21% of body weight at the highest dose.
- Wegovy (semaglutide) — a GLP-1 receptor agonist, injected once weekly. Clinical trials showed average weight loss of approximately 15% of body weight.
- Saxenda (liraglutide) — a GLP-1 agonist, injected daily. Available for over a decade with proven efficacy.
All three are prescription-only and require a clinical assessment to determine eligibility. They work by regulating appetite hormones and supporting feeling fuller after meals — mechanisms backed by clinical evidence rather than traditional herbal claims.
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: Referral to a tier 3 specialist weight management service through your GP is the NHS route. Eligibility typically requires a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure. Waiting lists vary significantly by region.
Private access: GPhC-registered online pharmacies offer prescription weight loss medication following an online clinical assessment with a UK-licensed prescriber. Available without NHS referral. You can calculate your personal BMI using our free BMI calculator to understand where you stand.
Speak with your GP about which option is right for you — they can advise on NHS availability in your area or discuss private options if that suits your circumstances better.
- 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.
Do plant-based weight loss supplements actually work?
Evidence for most plant-based supplements is limited. Some ingredients like green tea extract show modest benefits in studies, but effects are typically small — around 1–3 kg over several months. Prescription medications have much stronger clinical evidence. Always combine any supplement with diet changes and physical activity for best results.
What's the difference between supplements and prescription weight loss medication?
Supplements are unregulated and have limited clinical evidence. Prescription medications like Mounjaro and Wegovy are rigorously tested, licensed by MHRA, and show significant weight loss in clinical trials (15–21%). They require a prescription and clinical assessment to ensure they're safe for you individually.
Can I use plant-based supplements alongside prescription weight loss injections?
Always discuss this with your prescriber before combining any supplement with prescription medication. Some herbal ingredients can interact with medications or affect their absorption. Your GP or prescriber can advise whether any specific supplement is safe to use alongside your treatment.
How do I know if I'm eligible for prescription weight loss medication in the UK?
You typically qualify if you have a BMI of 30 or above, or 27–29.9 with weight-related health conditions. Our GLP-1 weight loss calculator can help you explore potential weight loss outcomes if eligible. Speak with your GP for a full eligibility assessment.
What's the difference between Mounjaro, Wegovy, and Saxenda?
All three are GLP-1-based medications licensed for weight management. Mounjaro is dual-acting (GIP + GLP-1), while Wegovy and Saxenda activate GLP-1 only. Mounjaro and Wegovy are weekly injections; Saxenda is daily. Clinical trial results vary slightly. Your GP or prescriber will recommend the most suitable option for you.
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.