Obesity is currently defined by the body mass index (BMI). BMI was not created to measure an individual’s health, though it is used to summarize the “fatness” of a population. Many consider it a flawed and, at best, limited measure. All criticisms withstanding, many studies have found that an increased BMI is associated with the risk of disease, particularly cardiovascular disease. This is thought to be due to the link between BMI and other factors, particularly one’s weight, and this has been a contradictory measure in studies that include waist circumference measurements. Read more about the link between waist circumference, BMI, and obesity.