Why do some scientists say to eat a certain amount of each a day?

Question

Who designs these allotments? And why?

Answer 1

Eating less may result in a deficiency disease.

Answer 2

The RDA was developed during World War II by Lydia J. Roberts, Hazel K. Stiebeling and Helen S. Mitchell, all part of a committee established by the U.S. National Academy of Sciences in order to investigate issues of nutrition that might "affect national defense" (Nestle, 35). The committee was renamed the Food and Nutrition Board in 1941, after which they began to deliberate on a set of recommendations of a standard daily allowance for each type of nutrient. The standards would be used for nutrition recommendations for the armed forces, for civilians, and for overseas population who might need food relief. Roberts, Stiebeling, and Mitchell surveyed all available data, created a tentative set of allowances for "energy and eight nutrients", and submitted them to experts for review (Nestle, 35). The final set of guidelines, called RDAs for Recommended Dietary Allowances, were accepted in 1941. The allowances were meant to provide superior nutrition for civilians and military personnel, so they included a "margin of safety." Because of food rationing during the war, the food guides created by government agencies to direct citizens' nutritional intake also took food availability into account.