BMI is the headline number; body fat percentage is the truth underneath. Here is how to measure it and what counts as healthy.
Body Mass Index is everywhere, but it is famously bad at telling muscle from fat. Body Fat Percentage (BFP) is the better metric: it measures what proportion of your body is actually adipose tissue, not just total weight relative to height. This guide explains how it is measured, what a healthy range looks like, and how to bring yours into a healthy zone.
BMI = weight (kg) ÷ height (m)². A muscular athlete at 1.80 m and 95 kg has a BMI of 29.3 — "overweight" — yet might be at 12% body fat (ripped). A sedentary office worker at 1.80 m and 75 kg has a BMI of 23.1 — "healthy" — but could carry 28% body fat (high risk).
BMI screens populations. Body fat screens individuals. Use both.
Recommendations from the American Council on Exercise (ACE), adjusted for age and sex:
Women:
Men:
Body fat tends to creep up with age. A healthy 25-year-old man might be at 14%; a healthy 55-year-old man might be at 20%, and that is normal.
Five methods, ranked rough → accurate:
1. Mirror & honesty. Free, surprisingly informative. 2. Tape measurement (US Navy method) — measure neck, waist, and (for women) hips, then apply a formula. ±3–4% accuracy. 3. Skinfold calipers — pinch tests at 3–7 body sites. ±2–3% accuracy with practice. 4. Bioelectrical impedance scales (BIA) — your smart scale. Cheap, repeatable, but easily skewed by hydration. Use at the same time of day under the same conditions. 5. DEXA scan, BodPod, hydrostatic weighing — gold-standard, ±1% accuracy, $50–150 per scan.
Pick one method and track the trend, not the absolute number. Going from 24% to 21% on the same scale matters more than the exact reading.
Body fat drops when energy in is less than energy out — but doing it without losing muscle takes specific tactics:
1. Aim for a moderate calorie deficit — 300–500 kcal/day, not crash dieting. 2. Hit your protein target — about 1.6–2.2 g per kg of bodyweight to preserve muscle in a deficit. 3. Lift weights 2–4×/week. Cardio burns calories; lifting preserves the metabolically active tissue. 4. Sleep 7–9 hours. Poor sleep raises cortisol and ghrelin, both fat-loss enemies. 5. Walk 8,000–12,000 steps a day. Non-exercise activity is the silent calorie killer. 6. Be patient. 0.5–1% body fat per month is a realistic rate.
Avoid: total carb-elimination diets, sub-1,200 kcal cuts, hours of daily cardio, and any plan that promises 1% per week.
Visceral fat — around organs, deep in the abdomen — is much more dangerous than subcutaneous fat (under the skin). A waist circumference above 102 cm for men or 88 cm for women is a stronger predictor of cardiovascular disease than BMI alone.
Can body fat go too low? Yes — under 5% (men) or 13% (women) is dangerous and almost impossible to maintain.
Why do BIA scales fluctuate so much? Hydration. A 1 kg water swing changes readings by 1–3%.
Is spot reduction real? No. You cannot choose where you lose fat. Genetics decides the order.
Try our BMI Calculator alongside body-fat estimates for a fuller picture.