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 17% Body Fat Mean?
A body fat percentage of 17% falls into the athletic category for most adults and is considered very healthy. This means approximately 17% of your total body weight is fat tissue, with the remaining 83% being lean body mass (muscle, bone, organs, and water). Body fat percentage is a more detailed measure of health than BMI alone, as it distinguishes between muscle and fat — something BMI cannot do. Understanding your body fat percentage gives you a clearer picture of your actual body composition and fitness level.
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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.
Body Fat Percentage Categories and Ranges
For women: 17% falls into the athletic category, which typically ranges from 14–20%. This is excellent for health and fitness.
For men: 17% is at the lower end of the fitness category (14–17%) and represents a very lean physique with visible muscle definition.
Body fat percentage categories are:
- Essential fat: 10–13% (women), 2–5% (men) — minimum needed for survival
- Athletic: 14–20% (women), 6–13% (men) — excellent fitness level
- Fitness: 21–24% (women), 14–17% (men) — healthy and active
- Acceptable: 25–31% (women), 18–24% (men) — normal for most adults
- Obese: 32%+ (women), 25%+ (men) — associated with health risks
At 17%, you're in a strong position for cardiovascular health, metabolic function, and overall fitness — whether you're male or female.
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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.
Body Composition vs BMI: Why Body Fat Matters
BMI (body mass index) cannot distinguish between muscle and fat. A muscular athlete might have a "high" BMI but low body fat and excellent health, whilst someone with a normal BMI might have elevated body fat and poor fitness. This is why body fat percentage is a more accurate health indicator than BMI alone.
At 17% body fat, your visceral fat (dangerous fat around organs) is likely low, which reduces your risk of type 2 diabetes, heart disease, and metabolic syndrome. Use our free BMI calculator alongside body fat assessment to get a complete picture of your health. For the most accurate body fat measurement, ask your GP about options like DEXA scans or hydrostatic weighing — these are far more precise than simple estimations.
- 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.
How do I measure my body fat percentage?
Common methods include skinfold calipers (inexpensive but requires skill), bioelectrical impedance scales (accessible but less accurate), DEXA scans (very accurate, available through some private clinics), and hydrostatic weighing (gold standard but less common in the UK). Your GP can advise on NHS-available options or recommend private clinics.
Is 17% body fat healthy?
Yes, 17% body fat is considered athletic and very healthy for both men and women. It indicates good fitness, strong muscle mass, and low risk of weight-related health conditions. Most health experts consider this an excellent target.
Can I have a normal BMI but high body fat?
Yes — this is called "skinny fat" and is possible, especially if you have low muscle mass. Someone might have a normal BMI but 35% body fat, which carries health risks. This is why body composition assessment matters alongside BMI.
How does 17% body fat compare to the average UK adult?
The average UK adult has body fat around 25–31%. At 17%, you're well above average in terms of fitness and lean body mass. This puts you in the athletic range and reduces your risk of obesity-related diseases.
What's the difference between body fat percentage and visceral fat?
Body fat percentage measures total fat in your body. Visceral fat is specifically the dangerous fat around your organs. At 17% overall body fat, your visceral fat is likely very low, which is protective against diabetes, heart disease, and metabolic problems.
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.