Nutrition, essential for your growth and development, helps fight infections, heal wounds, and provide energy to play and exercise. If you're well-nourished, you'll grow better, have stronger lungs, and feel better than those who are malnourished. You need extra calories because you use more energy breathing and fighting infections than people without CF. Also you may lose calories from malabsorption which is difficulty in digesting nutrients from food.

The energy your body gets from food is in the form of calories. Foods have different amounts of calories depending on whether they are made up of carbohydrates, protein or fat. Carbohydrates and protein have 4 calories per gram, but fat has 9 calories per gram. Eat a balanced diet rich in all food groups to receive enough calories to fuel your body for exercise and growth. People with CF need extra calories, about one-and-a-half times as much as a person without CF.