For what it's worth,
this site suggests that about 40% of mature, wild buck--about 72 pounds--can be used as meat (the rest being bones, hide, inedible organs, etc.). You could probably assume the same for other Medium game animals as well.
Now, this
does trivialize Supply quite a bit. After all, one deer plus one
gentle repose equal an entire journey's Supply for many people--assuming you don't have a Narrator who wants you to RP the problems that come with an all-meat diet, of course.

And that doesn't even take into consideration eating the monsters you kill. So it's can be hard to properly come up with a solution.
One possibility is that if you want to hunt bigger game like a deer, or you want to fish (a notoriously time-consuming activity if you're using a hook and line) you have to stay still. Your journey is delayed by one or more days while you hunt, kill, and butcher the animal. Journey activities take place while traveling, and that means you only can hunt a rabbit or other small animal and keep moving. If the party has no place to be and are just traveling for no real reason, then go ahead. If they have a schedule, though, deer are off the menu.
You could also up the number of monster encounters. Creatures will smell your fresh meat and either attack or try to raid your camp. Of course, the party could easily kill them or scare them off, most likely, unless you throw monsters above their CR at them--a 3rd- or 4th-level party whose camp is raided by a hungry hungry hydra, for instance. But that mostly works if you have a party who's willing to let an obviously higher-level creature alone.