consuming enough to meet the requirements of the body. Quite frequently
it is those who need more food who practice dieting. When there is
trouble with digestion, it is not always the amount or kind of food
which is at fault, but other habits may be such as to affect digestion.
The active out-of-door laborer can with impunity consume more food,
because there is greater demand for nutrients, and the food is more
completely oxidized in the body and without the formation of poisonous
waste products. The amount of food consumed should be sufficient to meet
all the demands of the body and maintain a normal weight.

234. Method of Preparation of Food.--The extent to which methods of
cooking and preparation influence completeness of digestion has not been
extensively investigated. As is well known, they have great influence
upon ease and comfort of digestion. During cooking, as discussed in
Chapter II, extensive physical and chemical changes occur, and these in
turn affect digestibility. When the cooking has not been sufficient to
mechanically disintegrate vegetable tissue, the digestive fluids fail to
act favorably upon the food. Cooking is also beneficial because it
renders the food sterile and destroys all objectionable microoerganisms
which, if they remain in food, readily undergo incubation in the
digestive tract, interfering with normal digestion. Prolonged heat
causes some foods to become less digestible, as milk, which digestion
experiments show to be more completely digested when fresh than when
sterilized. Pasteurized milk, which is not subjected to so high a
temperature as sterilized milk, is more completely digested. See Chapter
VII for discussion of sterilizing and pasteurizing milk.[38] The
benefits derived from the destruction of the objectionable bacteria in
foods are, however, greater than the losses attendant on lessened
digestibility due to the action of heat. The method of preparation of a
food affects its digestibility mainly through change in mechanical
structure, and modification of the forms in which the nutrients are
present.[5]

235. Mechanical Condition of Foods.--The mechanical condition of foods
as to density and structure of the particles and the extent to which
they are disintegrated in their preparation for the table influences
digestibility to a great extent. The mechanics of digestion is a subject
that has not been extensively investigated, and it is one of great
importance, as biological a