According to Atwater, the child in the second year of life, though weighing only a fifth or sixth as much as the adult, requires 3/10 of the standard adult ration, the relative excess being due to the fact that the child is rapidly depositing tissues, including fat. From the third to the fifth years, about 4/10 of the adult ration is required; from the sixth to the ninth years, 5/10; from the tenth to the thirteenth years, 6/10. Thereafter, there is a difference in habits of life so that the girl from 14 to 16, requires 7/10 of the adult ration; the boy 8/10. After this age continued growth and relative activity compensate for any average difference in weight between the youth and the adult. The adult woman requires 8/10 or 9/10 the ration of a man in the same walk of life. After the age of thirty, there is a gradual diminution of the dietetic need, and in old age, many individuals eat only about half the standard ration for an adult.

M. Allen Stark's Table Of Dietetic Needs In Childhood

(Above determined from actual consumption by groups of healthy children.)