The situation is more complex in children, where the BMI threshold of obesity varies with age and sex. The charts below show how the BMI obesity threshold changes with age for boys and girls.

Based on the chart below, you can calculate your BMI to see if it indicates you are underweight, a healthy weight, overweight, or obese. If you score below 18.5, then your BMI is underweight.

BMI stands for body mass index, explains Dr. Benedict Ifedi, MD, a family medicine doctor at Memorial Hermann. Dr. Glickman ...