According to a new study by a team of researchers from Michigan State University and Saginaw Valley University, the body mass index (BMI) does not accurately measure body fat. The researchers studied more than 400 students including athletes and found that most students' BMI did not accurately reflect actual body fat. BMI does not differentiate between muscle mass and body fat, which could portray a trimmed but muscular athlete as overweight. BMI only considers a person's height to weight ratio without taking into account the waist to hip ratio. A person with BMI of 18 to 24 is considered to be of normal weight, above 25 overweight and above 30 obese. Generally people considered overweight and obese have greater risk of developing lifestyle related illnesses such as diabetes and heart disease.