[King Grub]

Nitrogen balance at various levels of caloric intake. From 18 composite periods derived from 460 observations. (Adapted from CALLOWAY and SPECTOR, 1954).

http://www.unu.edu/unupress/food2/UI...#2.1.%20adults

It would appear, therefore, that the statements of both CALLOWAY and SPECTOR (1954) and MUNRO (1951; 1978), which claimed that the improvement in nitrogen balance caused by an increase in energy intake could be frustrated if intake of protein were inadequate, and that, conversely, the beneficial effects of an increase in protein intake could be inhibited by an inadequate energy intake, were applicable only under much more extreme conditions of protein or energy limitations than was generally the case for the analyzed studies. Within this range, that is from about 2100 kcal and 18 g protein to about 4200 kcal and 90 g protein/d for a 70 kg male, increases in both EI and NI appeared to be separately and individually effective in improving NB, and no stepwise progression, i.e., expected improvement in NB by increases in either NI or EI being frustrated by a lack of increase of the other, could be observed.