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 Healthy BMI Range for Women?
According to NHS guidance, a healthy BMI range for women is between 18.5 and 24.9 kg/m². This range applies to most adult women and is based on clinical evidence about health risk. However, if you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a slightly lower threshold of 18.5 to 22.9. Your BMI is just one indicator of health — it doesn't account for muscle mass, bone density, or where fat is stored. Use our free BMI calculator above to check your personal BMI instantly, and refer to the weight converter to switch between units if needed.
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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 What They Mean
The NHS uses standardised BMI categories to classify weight ranges in UK adults. These are based on NICE (National Institute for Health and Care Excellence) guidance and are used by GPs and NHS services across the country.
- Underweight: BMI below 18.5 — may indicate insufficient nutrition or underlying health issues
- Healthy weight: BMI 18.5–24.9 — associated with lowest health risk in clinical studies
- Overweight: BMI 25.0–29.9 — increased risk of type 2 diabetes and heart disease
- Obese (Class I): BMI 30.0–34.9 — significantly increased health risks
- Obese (Class II): BMI 35.0–39.9 — higher health risks than Class I
- Severely obese (Class III): BMI 40.0 and above — substantial health risks including type 2 diabetes and cardiovascular disease
For women of South Asian, Chinese, Black African, or Black Caribbean backgrounds, the NHS recommends lower BMI thresholds because research shows these groups face higher metabolic risk at lower BMI levels. The overweight threshold for these populations starts at BMI 23.0, and obesity begins at BMI 27.5.
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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 Support and When to Seek Help
If your BMI falls outside the healthy range, the NHS offers support through its weight management pathway. This typically starts with Tier 1 services — self-help resources, digital tools, and community-based programmes like the NHS Weight Loss Plan. Your GP can assess your individual health and refer you to specialist services if needed.
The NHS also recommends measuring your waist circumference alongside BMI, as where fat is stored matters for health. A waist measurement above 80cm (31.5 inches) for women indicates increased health risk; above 88cm (34.5 inches) indicates high risk. If you're concerned about your weight or health, book an appointment with your GP — they can provide personalised guidance and support appropriate to your circumstances.
- 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's the difference between BMI 24 and BMI 25 for women?
BMI 24 falls in the NHS healthy weight range (18.5–24.9), while BMI 25 is classified as overweight (25.0–29.9). This boundary is based on clinical research into health risk thresholds. However, BMI is a screening tool only — your GP will consider other factors like waist measurement, family history, and overall health when assessing your personal risk.
Why does the NHS recommend a lower BMI range for South Asian women?
Research shows that South Asian, Chinese, Black African, and Black Caribbean populations have a higher risk of type 2 diabetes and cardiovascular disease at lower BMI levels compared to other populations. The NHS therefore recommends a healthy BMI of 18.5–22.9 (rather than 18.5–24.9) for these groups to better reflect their individual health risk profile.
Is BMI the only thing I should use to check if I'm a healthy weight?
No. BMI has limitations — it doesn't distinguish between muscle and fat, and doesn't account for where fat is stored. The NHS recommends also measuring your waist circumference (a better indicator of belly fat and metabolic risk), considering your family history, and discussing your personal health with your GP. Our BMI calculator on this page shows your BMI, but your doctor can give more personalised guidance.
What should I do if my BMI is outside the healthy range?
Start by speaking to your GP, who can assess your individual health, rule out medical conditions affecting weight, and discuss your options. The NHS offers support through its weight management pathway, from self-help resources to specialist services. Your GP can also measure your waist circumference and discuss health risk factors specific to you.
How do I calculate my BMI using the NHS formula?
The NHS BMI formula is: weight (kg) divided by height (m) squared. For example, if you weigh 65kg and are 1.65m tall: 65 ÷ (1.65 × 1.65) = BMI of 23.9. Use our free BMI calculator on this page to calculate yours instantly — it works with both metric and imperial measurements.
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.