Food required for short rest is a good idea. It means the player can carry food all the time just in case they need a short rest. The food would act as an inventory slot limiter by the fact that it weighs something and will cause players to reach the carry weight limit faster.
If players want to play a bit more risky they can forgo the food for more carry weight. If you can only fast travel when standing in front of a rune, or other designated fast travel point, you wouldn't be able to rely on fast travel to get to safety anymore. In some situations it might be necessary to hunt for food and short rest rather than try to make it to a rune.
