Obesity is defined as having a body mass index (BMI) of 30 or more. BMI is a calculation that takes a person’s weight and height into account. However, BMI does have some limitations. According to the CDC, “Factors such as age, sex, ethnicity, and muscle mass can influence the relationship between BMI and body fat. Also, BMI does not distinguish between excess fat, muscle, or bone mass, nor does it provide any indication of the distribution of fat among individuals.” Despite these limitations, BMI continues to be widely used as an indicator of excess weight.