A BMI between 18.5 and 25 is considered "normal". People with a BMI of 25 or more are said to be overweight; with 30 and above, they are considered obese, and with 35 and above, they are considered "severely obese" (this used to be called "morbidly obese"). In general, the BMI number is a good quantifiable measurement of a person's obesity. However, it is a poor predictor in people who are very athletic, because a person with a higher than average amount of muscle tissue will weigh more than an average person, thus resulting in a BMI that is higher than normal, even if that person is very large.