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 Ideal BMI for Women?
The ideal BMI for women according to NHS guidance is between 18.5 and 24.9, which falls into the "healthy weight" category. However, your ideal personal BMI depends on several factors including your height, age, ethnicity, and overall health. For women of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends a slightly lower healthy range of 18.5 to 22.9 due to higher health risks at elevated BMI levels in these populations. BMI is a useful screening tool, but it has limitations — it doesn't account for muscle mass or where fat is stored on your body. Use our free BMI calculator above to find your personal BMI in seconds.
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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 formula divides your weight (kg) by your height in metres squared. According to NHS BMI categories, the standard ranges for adults are:
- Below 18.5: Underweight
- 18.5–24.9: Healthy weight (ideal range)
- 25.0–29.9: Overweight
- 30.0–34.9: Obese (Class I)
- 35.0–39.9: Obese (Class II)
- 40.0+: Severely obese (Class III)
For women of South Asian, Chinese, Black African, or Black Caribbean backgrounds, NICE guidance recommends lower thresholds: a healthy BMI range UK starts at 18.5 but extends only to 22.9, with overweight beginning at 23.0. This adjustment reflects research showing these groups face higher risks of type 2 diabetes and heart disease at lower BMI levels. Your GP can discuss which categories are most relevant to your individual health profile. Convert your weight between kg and stone using our weight converter to check where you stand.
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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 a structured weight management pathway to support you. Tier 1 involves self-help using tools like our free BMI calculator and progress tracker to monitor changes. Tier 2 includes GP-led behaviour change programmes such as the NHS Weight Loss Plan. For women with a BMI of 30 or above, or 27–29.9 with weight-related health conditions like type 2 diabetes or high blood pressure, Tier 3 specialist weight management services may offer prescription support. Remember that BMI limitations exist — having a BMI outside the "ideal" range doesn't automatically mean you're unhealthy, but it can indicate where health improvements might help. Book an appointment with your GP if you're concerned about your weight or 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's the difference between ideal BMI and healthy weight BMI for women?
Ideal and healthy weight mean the same thing — a BMI between 18.5 and 24.9 according to NHS guidance. Within that range, the exact "ideal" BMI varies by individual factors like muscle mass, bone density, and ethnicity. Your GP can help identify what's ideal for you personally.
Is the ideal BMI the same for all women?
No. Ethnicity significantly affects ideal BMI thresholds. Women of South Asian, Chinese, Black African, or Black Caribbean heritage have a lower healthy range (18.5–22.9) due to higher health risks at elevated BMI. Age, fitness level, and medical conditions also influence what's appropriate for you individually.
What if my BMI is just above 24.9 — am I overweight?
A BMI between 25.0 and 29.9 falls into the "overweight" category according to NHS definitions. This doesn't mean you're unhealthy, but it may indicate an increased risk of certain health conditions. Your GP can assess your individual circumstances, including waist measurement and medical history.
Can I have a high BMI and still be healthy?
BMI limitations are significant — it doesn't distinguish between muscle and fat. Athletes may have high BMI but low body fat. However, for most people, a BMI above 25 is associated with increased health risks. Your GP can assess your overall health profile rather than relying on BMI alone.
Where should my BMI ideally be if I'm 5ft 5in tall?
At 5ft 5in (165cm), the healthy BMI range translates to approximately 49–65kg (7st 9lbs–10st 3lbs). However, this is a guide only. Use our free BMI calculator above to calculate your personal healthy weight range based on your exact height and to track progress with our progress tracker.
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.