If a person is in a life threatening situation and can be saved by either doing a melacha or eating/drinking on Yom Kippur, what should he do?
If you look carefully, the verse says "a life that does not afflict itself [i.e. eat], shall be cut off ... anyone who does work, I will eradicate them." Rabbi Samson Raphael Hirsch points out that "eradicate" is a stronger language then "cut off"; someone gets too hungry or thirsty, nu that's one problem. But did they really, really need to go plow their field today?
Hence it would follow that eating would be less-bad than working.
(There's a different question of how many "counts" of the prohibited activity; how much eating are we talking about vs. how many different acts of working? But let's assume theoretically it's one unit of eating vs. one unit of working.)