We all know that food is important, but it cannot provide us with its purpose if it is not converted to the forms our body needs it to be, if we do not digest it properly. Except for water, vitamins and mineral salts that are directly absorbed by the body, complex substances needed to be broken down for our body to utilize it. And the very common process is called DIGESTION.
Digestion starts in the mouth, and so swallowing it like what we do when we are famished makes it skip the first stage. There are enzymes already in our mouth to act on the food...and continues on with the process as it passes through the next stages; esophagus, stomach, small intestine, and large intestine.
Complete digestion can be guaranteed after 24 to 72 hours, but what's important is the 6-8 hours when the food have passed the stomach and small intestine. This is where the enzymes are the most thus the food have been acted upon by them for our bodies use. Peak absorption of carbohydrate is in an hour, fat in 4-6 hours, and protein in between carbohydrates and fat.