While chicken breasts vary in size, a standard serving is 3 ounces. Chicken breasts are often eaten by people watching their weight due to their low calorie count and large amount of protein. A 3-ounce portion of boneless, skinless chicken breast has 102 calories and 19 grams of protein.
Increasing the amount of protein in the diet adds to a feeling of fullness and helps burn extra calories. It also can help decrease body fat and increase lean muscle mass. The Institute of Medicine recommends that up 35 percent of daily calories come from protein. Foods containing protein break down into essential amino acids.