Body Mass Index is a simple screening measure — it doesn't account for muscle mass, age, or body composition, so use it as a rough guide only.
BMI (Body Mass Index) is calculated as weight in kilograms divided by height in metres squared: BMI = weight(kg) / height(m)². It's a simple screening tool used to broadly classify people as underweight, normal weight, overweight, or obese, based on standard WHO/international thresholds.
BMI doesn't distinguish between muscle and fat, so it can misclassify very muscular individuals as 'overweight' and doesn't account for age, sex, or body composition differences — it's a useful quick screening indicator, not a diagnostic health measurement.
Under 18.5 is classified as underweight, 18.5-24.9 as normal weight, 25-29.9 as overweight, and 30 and above as obese, under the commonly used international classification.
Not particularly — since muscle is denser than fat, muscular individuals often have a higher BMI despite having low body fat, which is a well-known limitation of the BMI measure.
Not exactly — some health guidelines suggest slightly different BMI thresholds for certain populations (for instance, some Asian population guidelines use lower cutoffs for 'overweight'), and BMI ranges for children are calculated differently using age- and sex-specific percentiles.