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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What Does a BMI of 27 Mean?
A BMI of 27 falls in the overweight category according to NHS guidelines, which classify 25.0 to 29.9 as overweight for most UK adults. However, your BMI tells only part of the story about your health. This guide explains what a BMI of 27 means, how to interpret calculator results, and how body composition metrics like body fat percentage offer additional insight beyond BMI alone. Use our free BMI calculator above to check your personal BMI and explore what it means in context.
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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.
How to Interpret a BMI of 27
A BMI of 27 indicates you are in the overweight category according to NHS standards. This does not mean you are unhealthy — many factors influence health beyond BMI, including fitness level, muscle mass, diet quality, and stress management. For adults of South Asian, Chinese, Black African, or Black Caribbean heritage, the NHS recommends lower thresholds, meaning a BMI of 27 may carry higher health risk for these groups.
To move into the healthy weight range (18.5–24.9 BMI), you would typically need to lose weight depending on your height. For example, at 1.75m tall (5ft 9in), a BMI of 27 corresponds to approximately 82.7kg. The healthy weight range for this height is roughly 56.6–76.2kg. Our weight converter can help you check these figures in stone and pounds. It's important to note that BMI does not distinguish between muscle and fat — athletes with high muscle mass may have elevated BMI but low body fat percentage, which is perfectly healthy.
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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.
BMI vs Body Composition — Which Matters More?
While BMI is a useful screening tool, body composition — the ratio of fat to lean body mass — often provides a clearer picture of health. Two people with identical BMI can have very different body fat percentages depending on muscle mass. Body fat percentage ranges vary by gender: for women, 21–24% is considered fitness level; for men, 14–17% is fitness level. Healthy body fat for women sits around 25–31%, while for men it's 18–24%.
BMI has real limitations: it ignores where fat is stored (visceral fat around organs is more harmful than subcutaneous fat), doesn't account for age-related muscle loss, and may overestimate health risk in very muscular individuals. For a complete picture, combine BMI assessment with waist circumference measurement (men over 94cm have increased health risk; women over 80cm have increased risk) and consider a body fat calculator if available. Talk to your GP for personalised health guidance.
- 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.
Does a BMI of 27 mean I'm unhealthy?
Not necessarily. BMI is a screening tool, not a diagnosis. A BMI of 27 indicates you're overweight by NHS standards, but health is determined by many factors including fitness, diet, stress, sleep, and family history. Some people with BMI 27 are very healthy; others may benefit from lifestyle changes. Your GP can assess your individual risk factors.
How much weight would I need to lose to reach a healthy BMI?
It depends on your height. At 1.75m (5ft 9in), you'd need to reach approximately 76kg or less. At 1.65m (5ft 5in), approximately 67kg or less. Use our free BMI calculator above to enter your height and see the healthy weight range for you personally — then our weight converter helps you see this in stone and pounds.
Is body fat percentage more important than BMI?
Both metrics are useful but measure different things. BMI is quick and easy; body fat percentage is more specific but harder to measure accurately. Ideally, assess both. Someone with BMI 27 but low body fat (high muscle) may be healthier than someone with BMI 24 but high body fat. A GP or fitness professional can help interpret your personal results.
Why do South Asian and Black African adults have different BMI thresholds?
The NHS recognises that these populations develop weight-related health conditions like type 2 diabetes and cardiovascular disease at lower BMI levels due to genetic and metabolic differences. For these groups, overweight status begins at BMI 23, not 25. If you're from these backgrounds, discuss the appropriate BMI range for you with your GP.
What's the difference between visceral fat and body fat percentage?
Body fat percentage measures total fat as a percentage of body weight. Visceral fat is fat stored deep around your organs, which is metabolically more harmful and linked to increased disease risk. You can't measure visceral fat at home, but waist circumference is a proxy — a larger waist suggests more visceral fat. This is why waist measurement matters alongside BMI.
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.