Is it true that complex substances have to be broken down into simpler ones before they can be used for the upkeep and growth of the body?

It is true that complex substances, such as carbohydrates, proteins, and fats, found in food have to be broken down into simpler molecules before they can be used by the body for energy and growth. This process is known as digestion, which is the mechanical and chemical breakdown of food.  To achieve this, organisms use bio-catalysts called enzymes.