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BMI (Body Mass Index) is a numerical value calculated from your weight and height. The formula is: BMI = weight in kilograms divided by height in meters squared (kg/m²). It is used as a simple screening tool to categorize weight status into underweight, normal weight, overweight, and obese ranges.
BMI categories defined by the World Health Organization are: Underweight (BMI below 18.5), Normal weight (BMI 18.5 to 24.9), Overweight (BMI 25.0 to 29.9), and Obese (BMI 30.0 and above). These ranges apply to adults aged 20 and older.
BMI is a useful screening tool but has limitations. It does not distinguish between muscle mass and fat mass, so athletes or muscular individuals may have a high BMI without excess body fat. It also does not account for fat distribution, bone density, age, or sex differences. BMI should be considered alongside other health indicators like waist circumference, blood pressure, and cholesterol levels.
For most adults, checking your BMI once every few months is sufficient to track trends. If you are actively working on weight management, monthly check-ins can help monitor progress. Remember that daily weight fluctuations are normal — focus on long-term trends rather than individual measurements.