The size of the body has more influence than its weight upon the quantity of food consumed. In infant feeding the relationship is made the subject of careful study (see Infant Feeding), but in adults there is more variation. As a general rule, persons of large frame eat in proportion to their size, and vice versa, but there are many exceptions familiar to all, and some very corpulent persons are very abstemious at the table. Because most persons eat more than they really need, a man of large frame can often eat less than one of small size, and yet have plenty.

Attempts have been made to demonstrate that a preponderance of animal or vegetable food respectively, or of some particular system of diet, influences the stature of men. Of course, children who receive insufficient food or food poor in quality may be half grown, but beyond that fact theories as to the specific influence of different classes of food upon the development of the body are founded upon ignorance of the natural history of the different races of man. The diet of Bushmen, Australians, and Fuegians presents instructive examples of tribes with large or small bodies, demonstrating that " it is not quality or monotony of food, but its quantity that affects development" (Gerland).