Body Mass Index (BMI) measures the relationship between weight and height and is one of the most accurate ways to determine if extra pounds pose health risks. In June of 1998, the federal government announced guidelines which established a definition of a healthy weight. A BMI score of 20-24 is associated with the lowest health risk, while a BMI of 25-29.9 is considered overweight. Individuals who have a BMI in the range of 25-34.9 and who have a waist size of over 35 inches for women or 40 inches for men are considered to be at an especially increased risk for health problems. Exceptions to a high BMI score include athletes whose BMI is high due to increased muscle mass, and pregnant or lactating women.