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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Wegovy and BMI — What the NHS Recommends
Wegovy (semaglutide) is a prescription-only weight management injection available in the UK, and BMI is the key starting point for eligibility assessment. The NHS uses BMI categories to determine who may benefit from prescription weight loss treatment, including Wegovy. Understanding your BMI range and how it relates to NHS weight management pathways can help you know whether to speak with your GP about your weight health. Use our free BMI calculator above to check your personal BMI instantly, then read the NHS context below.
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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.
NHS BMI Categories and Wegovy Eligibility
The NHS BMI formula divides adults into five main categories based on health risk. According to NHS guidelines, a healthy BMI is between 18.5 and 24.9. Adults with a BMI of 25 to 29.9 are classified as overweight, while a BMI of 30 and above indicates obesity.
For Wegovy eligibility, the NHS typically considers prescription treatment for adults with:
- BMI of 30 or above (obesity), OR
- BMI of 27 to 29.9 (overweight) with at least one weight-related health condition such as type 2 diabetes, high blood pressure, or cardiovascular disease
For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds due to higher health risks at lower BMI ranges. This means eligibility may start at a BMI of 27.5 or above for these groups. NICE guidance emphasises that BMI is a useful screening tool but has limitations—it does not account for muscle mass, frame size, or where fat is stored, so your GP will assess your overall health context, not BMI alone.
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 Weight Management Pathway and Seeking Help
The NHS provides a structured weight management pathway starting with your GP. Tier 1 includes self-help resources and community programmes. If your GP believes you need specialist support, you may be referred to Tier 3 specialist weight management services, where Wegovy and other prescription medications may be considered following a clinical assessment.
To discuss your weight health with the NHS, contact your GP with your BMI and any weight-related health concerns. Your GP can calculate your BMI, discuss your health risks, and determine whether referral to specialist services is appropriate. Access to Wegovy through the NHS varies by region—waiting lists can be lengthy in many areas. Alternatively, private prescribing services offer faster access following an online clinical assessment with a UK-licensed prescriber. Either route requires prescription only; Wegovy is never available over-the-counter.
- 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.
What BMI qualifies me for Wegovy on the NHS?
NHS eligibility for Wegovy typically requires a BMI of 30 or above, or a BMI of 27–29.9 with a weight-related health condition like diabetes or high blood pressure. Lower BMI thresholds apply for South Asian, Chinese, Black African, and Black Caribbean adults. Your GP will assess your individual circumstances.
How do I calculate my BMI?
BMI is calculated as weight (kg) divided by height (metres) squared. For example, a person weighing 70kg and 1.75m tall has a BMI of approximately 22.9 (healthy weight). Use our free BMI calculator above for gradual improvement in your preferred units (kg, stone, or pounds).
What are the NHS BMI categories?
NHS BMI categories are: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25–29.9), obese (30–34.9), and severely obese (40+). Each category reflects increasing health risk, though BMI should be considered alongside other factors like waist circumference and overall health context.
Does Wegovy work if I'm overweight but not obese (BMI 25–29.9)?
Yes, if you have a weight-related health condition like type 2 diabetes, high blood pressure, or cardiovascular disease, you may be eligible for Wegovy even with a BMI under 30. Your GP or prescriber will assess whether prescription treatment is appropriate for your individual health profile.
What's the difference between NHS and private access to Wegovy?
NHS access requires GP referral to specialist tier 3 weight management services, with variable waiting lists by region. Private access is through online prescribing following a clinical assessment, typically faster but involves private costs. Both routes require a valid prescription from a UK-licensed prescriber and clinical eligibility 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.