Body mass index (BMI) is one way to estimate a person's body fat that takes into consideration the person's height. BMI is calculated using a person's weight and height. In children and teens, BMI is used to find out if a child or teen is underweight, of a healthy weight, overweight, or obese. A child's body fat changes with age. Also, girls and boys differ in their amount of body fat as they mature. This is why BMI for children, also known as BMI-for-age, includes gender and age.
Cystic fibrosis (CF) is an inherited disease that mostly affects the respiratory and digestive systems. About 30,000 children and young adults in the U.S. have CF. Most of them are descendants of people from northern Europe. Find out more about CF by taking this quiz, based on information from the National Institutes of Health.