Food gives us energy and is essential to our growth and activity, but water, though it does not provide a single calorie, is the environment in which the whole digestive and metabolic chemistry is carried out. So sometimes the sensation of hunger that some people feel during digestion after meals, can mask their need for water; they should then drink a glass or two of water and wait ten or fifteen minutes until the feeling of hunger has passed.
In a strict energy assessment, the oxidation of food in the body has the following energy yields
The calorie content of food is the result of the combination of its composition and mainly its water content. The higher the food water content, the lower its calorie value.