Question 1

BMI categories (WHO)

Accepted Answer

<18.5 underweight · 18.5–24.9 normal · 25.0–29.9 overweight · ≥30 obese (further split into Class I, II, III above 30/35/40). The thresholds were derived from large adult-population studies and don't apply well to athletes, the elderly, or certain ethnicities.

Question 2

What BMI doesn't measure

Accepted Answer

BMI uses height and weight. It can't see body fat percentage, muscle mass, fat distribution, bone density, or fitness level — all of which affect what your weight actually means for your health. A 95 kg sprinter and a 95 kg sedentary person of the same height have identical BMIs and very different bodies. Treat the number as the start of a conversation, not the answer.

Question 3

Better health indicators

Accepted Answer

Modern guidance pairs BMI with waist circumference, waist-to-height ratio, blood pressure, and resting metabolic markers (lipids, glucose). Those together give a much fuller picture than BMI alone. For sport-context body composition, DEXA scans, calliper testing, or bioelectrical impedance are far more accurate. None of these replace a clinician — but they give a clinician more to work with.

Question 4

Population caveats

Accepted Answer

WHO BMI thresholds were derived primarily from European-ancestry adult populations. Some Asian populations show higher cardiovascular and diabetes risk at lower BMI values; many countries (e.g. India, Singapore) use modified cut-offs (overweight from BMI 23+). Children and adolescents use percentile-on-age charts entirely, not the adult thresholds. Pregnancy and elderly individuals also need different benchmarks.

BMI 計算機 — 公制同英制

BMI 分類（WHO）

BMI 度唔到嘅嘢

更好嘅健康指標

人口差異要留意

唔會做嘅嘢