Body mass index can be used to judge whether a person is overweight or obese. Generally speaking, a normal person's body mass index is between 18.5 and 24.9, with over 25 being overweight and over 30 being obese.
Besides body mass index, there are other methods to judge whether a person is overweight or obese, such as standard weight method and waist circumference measurement. But the body mass index is a simple and practical method, which can accurately reflect a person's physical condition.