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All living things must have an unceasing supply of energy and matter. The transformation of this energy and matter within the body is called metabolism.


Catabolism is destructive metabolism. Typically, in catabolism, larger organic molecules are broken down into smaller constituents. This usually occurs with the

Recommended Dietary Allowances (RDAs)

For many years the Food and Nutrition Board of the United States National Academy of Sciences has taken responsibility for establishing guidelines on what quantities of the various nutrients should be eaten by human males and females at various ages. These were called RDAs (for Recommended Dietary Allowances, and often referred to as Recommended Daily Allowances). They provide the data on which food labels are based.

In 1997, the Institute of Medicine of