This article is from the Bicycles FAQ, by Mike Iglesias with numerous contributions by others.
This term refers to the quantity of nutrients in a food for its accompanying
caloric(energy) value. A twinkie contains much energy but few vitamins and
minerals so has a low nutrient density. Liver, on the other hand, has a
moderate amount of calories but is rich in vitamins and minerals and is
considered a high nutrient density food.
Basically, one must meet his/her nutrient requirements within the
constraints of his/her energy demands. Persons with a low daily
activity level have a low energy demand and in order to maintain their
body weight must eat high nutrient density foods. As already
mentioned, a cyclist has an increased energy demand but no significant
increase in nutrient requirements. Because of this he/she can eat
foods with a lower nutrient density than the average person. This
means that a cyclist can be less choosy about the foods that are eaten
provided he/she realizes his/her specific nutrient and energy
requirements that must be met.
 
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