BMI & Health — Understanding Your Body Mass Index Numbers

The 'normal' range of 18.5-24.9 is associated with the lowest risk of chronic diseases like diabetes, heart disease, and hypertension.

Formula: BMI = Weight (kg) ÷ Height² (m²)

Example: 70 kg, 170 cm (1.7 m) BMI = 70 ÷ (1.7 × 1.7) = 70 ÷ 2.89 = 24.2 (Normal)

BMI is a useful screening tool but has significant limitations:

1. Doesn't distinguish muscle from fat: A muscular athlete with 10% body fat could have a BMI of 28 ('overweight').

2. Doesn't account for body composition: Two people with the same BMI can have very different health risks based on fat distribution.

3. Age and sex: BMI categories were developed for adults 20+. They don't apply to children, pregnant women, or elderly.

4. Ethnicity: South Asians have higher health risks at lower BMIs. Some guidelines suggest BMI 23+ (not 25+) as overweight for Asian populations.

Better metrics to track alongside BMI: Waist circumference (<90 cm men, <80 cm women), waist-to-hip ratio, body fat percentage.

The WHO has proposed lower BMI cutoffs for Asian populations due to higher metabolic risks:

Under Asian cutoffs, a BMI of 24 would be classified as 'overweight' rather than 'normal'. This is important for Indian users of our BMI Calculator.