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 the Average Female BMI in the UK?
The average BMI for UK women is approximately 27.4, which falls into the overweight category according to NHS guidelines. However, the healthy BMI range for all adults is 18.5 to 24.9. It's important to understand that average doesn't mean healthy — knowing your personal BMI and how it relates to your individual health is what matters. Use our free BMI calculator above to find your own BMI and see where it falls on the NHS scale.
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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 are the standard measurement used across UK health services. A healthy BMI ranges from 18.5 to 24.9, while the average female BMI of 27.4 sits in the overweight range (25.0 to 29.9). The full BMI range UK breakdown is: underweight (below 18.5), healthy weight (18.5–24.9), overweight (25.0–29.9), obese (30.0–34.9), and severely obese (40.0+).
NICE guidance emphasises that BMI is a useful screening tool, but it has important BMI limitations — it does not distinguish between muscle and fat, nor does it account for where fat is stored on the body. For example, an athlete may have a high BMI but low body fat. For this reason, NHS professionals often also assess waist circumference and overall health context alongside BMI.
For women of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds: a healthy BMI starts at 18.5 but extends only to 22.9, with overweight beginning at 23.0. This is because these groups face higher health risks from excess weight at lower BMI levels.
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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 is 25 or above, the NHS recommends speaking with your GP, who can discuss your individual health context. The NHS offers a structured weight management pathway starting with tier 1 support — self-help resources and community programmes. Your GP can refer you to tier 2 or 3 specialist services if needed, where evidence-based weight loss support, dietary advice, and in some cases prescription medication may be offered.
You don't need to wait until your BMI reaches a certain threshold to seek help — many GPs will support weight management goals at any stage. The NHS Weight Loss Plan (a free 12-week programme) is available to all UK adults. Beyond BMI, consider your overall health picture: energy levels, ability to exercise, blood pressure, blood sugar control, and family health history all matter. Calculate your BMI using the free tool on this page, then have a conversation with your GP about what's right for you.
- 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 average female BMI and a healthy BMI?
Average female BMI in the UK is approximately 27.4 (overweight category), but the healthy BMI range is 18.5–24.9 according to NHS guidelines. Average reflects the current population, not what's healthiest. Your individual BMI and health context matter more than how you compare to average.
Why do ethnic groups have different NHS BMI thresholds?
Research shows that South Asian, Chinese, Black African, and Black Caribbean adults face higher health risks from excess weight at lower BMI levels. The NHS recommends these groups use different thresholds — healthy BMI is 18.5–22.9 rather than 18.5–24.9 — to identify risk more accurately.
How do I use the BMI formula to calculate my own BMI?
The BMI formula is: weight (kg) ÷ height (m)². For example, if you weigh 65kg and are 1.63m tall, your BMI is 65 ÷ (1.63)² = 24.5. Our free BMI calculator above does this instantly — just enter your weight and height in kg and cm.
What should I do if my BMI is above 25?
First, speak with your GP to discuss your individual health picture. BMI is one screening tool, but it doesn't account for muscle mass, fitness level, or where fat is stored. Your GP can assess your overall health and discuss whether weight management support is appropriate for you.
Are there BMI limitations I should know about?
Yes — BMI doesn't distinguish between muscle and fat, doesn't account for age or body composition, and may not be accurate for very muscular individuals, elderly people, or during pregnancy. Always discuss your personal BMI with your GP rather than relying on BMI alone.
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.