So the 1e/2e ogre (9 feet tall, 300-350 pounds) needed to eat more adventurers to reach average weight?
Assuming my maths is correct and the stats of the 1e/2e ogre are unquestionable, it heavily points to C being 24, which means that Ogres are actually made of something resembling pine wood (C=28) rather than flesh...
Mind I haven't figured into that calculation that creatures of an Orcish build should actually have the final result multiplied by 1.3, which is pretty remiss of me.