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
What Is a Good BMI Range According to NHS Guidelines?
A good BMI range according to NHS guidance is between 18.5 and 24.9 for most UK adults. BMI (body mass index) is calculated using your height and weight, and it's one of the main tools the NHS uses to screen for potential health risks. However, BMI has limitations — it doesn't account for muscle mass or where fat is stored on your body. Your GP can provide personalised advice about what your BMI means for your individual health. Use our free BMI calculator above to find your personal BMI instantly.
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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 What They Mean
The NHS uses standardised BMI categories to assess weight and health risk. Here's how NHS classifies BMI ranges:
- Healthy weight: BMI 18.5–24.9 (low health risk)
- Overweight: BMI 25.0–29.9 (increased health risk)
- Obese Class I: BMI 30.0–34.9 (high health risk)
- Obese Class II: BMI 35.0–39.9 (very high health risk)
- Severely obese (Class III): BMI 40.0+ (extremely high health risk)
Importantly, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower BMI thresholds because these populations face higher cardiovascular and diabetes risks at lower weights. For these groups, a healthy BMI range is 18.5–22.9, and the overweight threshold starts at 23.0. NICE guidance emphasises that ethnicity-adjusted thresholds are essential for accurate health assessment.
Clinically BackedWeight Loss
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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 When to Seek Help
If your BMI falls outside the healthy range, the NHS offers a structured weight management pathway. Tier 1 services include self-help tools, digital programmes, and community weight management groups — many are free or low-cost. Your GP can refer you to Tier 2 for behaviour change support, or Tier 3 specialist weight management services if you need more intensive help. At Tier 3, you may be assessed for prescription weight loss medication if appropriate. Availability varies by region, so speak to your GP about what's available in your area. Track your weight progress using our free progress tracker to support your journey.
- 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 range is considered healthy by the NHS?
The NHS defines a healthy BMI as 18.5–24.9 for most UK adults. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower healthy range of 18.5–22.9 due to higher health risks at higher BMIs in these populations.
What does the BMI formula mean and how is it calculated?
BMI is calculated by dividing your weight in kilograms by your height in metres squared (kg/m²). For example, if you weigh 70kg and are 1.75m tall, your BMI is 70 ÷ (1.75)² = 22.9, which falls in the healthy weight range. Use our BMI calculator to work this out instantly.
What are the limitations of BMI as a health measure?
BMI doesn't distinguish between muscle and fat — athletes may have a high BMI but low body fat. It also doesn't account for where fat is stored (waist circumference matters) or age-related muscle loss. BMI is a screening tool, not a diagnosis. Your GP can assess your individual health beyond BMI.
What should I do if my BMI is outside the healthy range?
Start by speaking to your GP, who can offer personalised advice. The NHS offers a weight management pathway starting with Tier 1 support (digital tools and community groups), progressing to specialist services if needed. Even a 5–clinically studied weight loss can significantly improve health outcomes.
Are BMI thresholds different for children?
Yes, children use age and sex-specific growth charts (UK90 reference), not adult BMI categories. If you're concerned about a child's weight, speak to your GP or health visitor. The NHS has a separate Healthy Weight Calculator specifically for children.
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.