While a later period, the RMFT era, Etienne Provost, was a major figure in the western fur trade history and was known as the man of the mountains. He was described in the late 1830's as having a corpus as round as a porpoise and was not a fort bound partisan or other employee, but rather a leader of fur brigades during the early 1800's up to his death in 1850. My ancestor, Ole Bill Burrows, sketched by A. J. Miller in 1837, shows a definite pot belly, a still common occurrence amongst the Burrows men once we reach our late 20's.
So while perhaps not common, not all "players" were small nor svelte...