Show me a table of BMI ranges and weight categories

The Body Mass Index (BMI) is a screening tool used to categorize weight status. The following ranges are based on standard adult definitions provided by the CDC and NIH:

How does BMI differ for children?

While the calculation for BMI (weight divided by height squared) is the same for children and teens as it is for adults, the criteria used to interpret the meaning of the BMI number are different. For children and teens, BMI is age- and sex-specific and is often referred to as BMI-for-age.

This is because children's body fat changes as they grow, and boys and girls differ in body fat maturation. Therefore, doctors use growth charts to determine a percentile ranking (e.g., 85th percentile) rather than absolute cut-off numbers.

What are realistic weight loss goals per week?

According to the NIH and CDC, a safe and sustainable rate of weight loss is 0.5 to 1 kg (1 to 2 pounds) per week. Losing weight at this gradual pace helps ensure that you are losing fat rather than water weight or lean muscle tissue.

To achieve a loss of 1 pound per week, you generally need a calorie deficit of about 3,500 calories per week, or roughly 500 calories per day. Drastic calorie restriction often leads to metabolic adaptation, making it harder to keep the weight off long-term.

How do BMI calculators account for muscle mass?

This is the most significant limitation of the standard BMI formula: It does not distinguish between excess fat, muscle, or bone mass.

Athletes or individuals with high muscle mass may have a high BMI (classifying them as "overweight" or "obese") despite having low body fat. Conversely, elderly adults may have a "healthy" BMI but have lost significant muscle mass (sarcopenia) and gained hidden visceral fat. Therefore, BMI should be used as an initial screening tool, not a diagnostic measure of health.