The food requirements of an organism. The foods that constitute the human diet should contain vitamins, mineral salts (see essential element), and dietary fibre as well as water, carbohydrates and fats (which provide energy), and proteins (required for growth and maintenance). A balanced diet contains the correct proportions of these nutrients, which will vary depending on the age, sex, body size, and the level of activity of the individual. An inadequate supply of different food types in the diet can lead to malnutrition.