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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Understanding BMI for Women — NHS Guidelines
BMI (body mass index) is a useful health screening tool that helps assess whether your weight is in a healthy range for your height. For women in the UK, the NHS provides clear BMI categories and guidance to help you understand what your measurement means. This guide explains how BMI works, what the healthy range is, and what NHS support is available if you want to improve your health. Remember that BMI is just one aspect of overall health — other factors like fitness, diet, and wellbeing also matter.
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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 BMI categories for women are the same as for men and are based on your weight in kilograms divided by your height in metres squared. Here's what each range means:
- Below 18.5 — Underweight. May indicate nutritional deficiency; discuss with your GP if concerned.
- 18.5 to 24.9 — Healthy weight. This is the target range for most women.
- 25.0 to 29.9 — Overweight. Increased health risks; lifestyle changes recommended.
- 30.0 to 34.9 — Obese (Class I). NHS recommends weight management support.
- 35.0 to 39.9 — Obese (Class II). Specialist NHS support usually recommended.
- 40.0+ — Severely obese (Class III). Access to tier 3/4 NHS weight management services.
If you're of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — a healthy BMI for these groups starts at 18.5 to 22.9, as these populations face higher health risks at standard BMI levels. Use our free BMI calculator above to find your personal BMI instantly.
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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
The NHS offers a structured weight management pathway with four tiers of support. At tier 1, you can access self-help tools, digital programmes, and community weight loss services. Your GP can refer you to tier 2 for behaviour change support and structured programmes like the NHS Weight Loss Plan. If you have a BMI of 30+ with health conditions, or BMI 35+, you may qualify for tier 3 specialist multidisciplinary services, where prescription weight loss medication may be considered. Tier 4 offers bariatric surgery for severe obesity with significant complications. Contact your GP to discuss which tier is appropriate for you, or use our free GLP-1 weight loss calculator to explore what weight loss might mean for your health.
- 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 is the healthy BMI range for women in the UK?
According to NHS guidelines, the healthy BMI range for women is 18.5 to 24.9 kg/m². This range applies to most adult women. However, if you are of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a lower healthy range of 18.5 to 22.9. Always discuss your personal healthy weight with your GP, as it depends on your individual health, fitness, and medical history.
Is BMI different for women than for men?
No, the BMI formula and categories are the same for both women and men. BMI is calculated as weight (kg) divided by height (metres) squared. The same NHS BMI categories apply. However, women tend to have naturally higher body fat percentages than men at the same BMI, so some health professionals also consider body composition alongside BMI when assessing individual health.
What does it mean if my BMI is in the overweight range?
If your BMI is between 25.0 and 29.9, you fall into the overweight category. This doesn't mean you're unhealthy, but it does indicate an increased risk of weight-related health conditions like type 2 diabetes, high blood pressure, and heart disease. The NHS recommends lifestyle changes — diet and physical activity — to move towards the healthy range. Your GP can offer tailored advice and support.
Can I get weight loss medication on the NHS?
Yes, prescription weight loss medications like Mounjaro (tirzepatide) and Wegovy (semaglutide) are available on the NHS for eligible adults. You typically need a BMI of 30+ with health conditions, or BMI 35+, and are usually referred to a specialist tier 3 weight management service. Availability varies by region. Speak to your GP about referral, or explore our weight converter and BMI calculator to understand your current health metrics.
What are the limitations of BMI for women?
BMI doesn't distinguish between muscle and fat — so athletes may have a high BMI but low body fat. It also doesn't account for where fat is stored; waist circumference matters too. BMI is less accurate during pregnancy and may not fully reflect health in older women due to natural muscle loss. Use BMI as a screening tool alongside other health measures, and always discuss your individual health with your GP.
Ready to take control of your weight loss journey?
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