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
Obese in Women — What NHS Categories Tell You
Understanding whether you're obese is an important part of managing your health. In the UK, the NHS uses BMI (Body Mass Index) to categorise weight, with obesity defined as a BMI of 30 or above. However, BMI is just one indicator — your waist measurement and overall health context matter too. This guide explains the NHS definitions, how to check your BMI, and what to do next if you're concerned about your weight.
10,000+ calculations today · NHS-aligned thresholds · 100% free
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 for Women — What Counts as Obese?
The NHS defines weight categories using BMI, calculated from your height and weight. For women, the categories are:
- Underweight: BMI below 18.5
- Healthy weight: BMI 18.5–24.9
- Overweight: BMI 25–29.9
- Obese (Class I): BMI 30–34.9
- Obese (Class II): BMI 35–39.9
- Severely obese (Class III): BMI 40 and above
If you have a BMI of 30 or higher, you fall into the obese category according to NHS guidelines. However, this is a screening tool only — it doesn't account for muscle mass, where fat is stored, or your individual health picture. Use our free BMI calculator above to check your personal BMI instantly and understand where you fall on this scale.
For women of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds — obesity begins at BMI 27.5 or above due to higher cardiovascular and diabetes risk in these populations.
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
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.
Waist Measurement — A Complementary Health Check
Waist circumference is an important complementary check alongside BMI. The NHS identifies increased health risk at different waist measurements:
- Increased risk: Waist circumference over 80 cm (31.5 inches)
- High risk: Waist circumference over 88 cm (34.5 inches)
A larger waist measurement can indicate more fat stored around your organs, which carries greater health risks than fat stored elsewhere. Even if your BMI is in the healthy range, a high waist measurement may suggest health intervention is needed. Measure your waist at the midpoint between your lowest rib and hip bone. If your waist measurement falls into the high-risk category, speak to your GP about next steps 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's the difference between overweight and obese according to NHS guidelines?
According to the NHS, overweight is a BMI of 25–29.9, while obese is a BMI of 30 or above. Both categories indicate increased health risk compared to a healthy BMI (18.5–24.9). The distinction helps guide what health interventions might be appropriate.
Can I be at a healthy weight but still have health risks?
Yes. BMI doesn't account for muscle mass or where fat is stored. A high waist measurement indicates increased risk even at a healthy BMI. This is why the NHS recommends checking both BMI and waist circumference for a complete picture of metabolic health.
I'm obese — what should I do next?
Start by speaking to your GP. They can assess your overall health, discuss lifestyle changes like diet and physical activity, and determine if you'd benefit from support through NHS weight management services or other interventions. Even modest weight loss (5–10%) can improve health outcomes.
Why do South Asian women have different BMI thresholds?
Research shows South Asian, Chinese, Black African, and Black Caribbean populations face higher risks of type 2 diabetes and heart disease at lower BMI levels. The NHS recommends lower thresholds (obesity starts at BMI 27.5) for these groups to identify health risks earlier.
Is BMI accurate for everyone?
BMI is a useful screening tool but has limitations. It doesn't distinguish between muscle and fat, doesn't account for age-related muscle loss, and is less accurate during pregnancy. Your GP can help interpret your BMI in the context of your individual health and family history.
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.