If you go into the settings and go to the "E" tab you can disable physics damage and disable food tolerance. This makes it much easier to survive in the game, and is in my opinion a lot more fun this way.
There are MRE's hidden throughout the base. There are also MRE's at the stonehenge east of Whiskey tower and since you can also get the shovel from stonehenge, it's worth it to stop there early on. If you buy an item box and some trash bags you can fill the box with garbage and sell it to the drone. This will give you money to buy more food.
If you are out exploring you can also find chicken burgers and mushrooms. The white puffball mushrooms are edible. Don't eat the red mushrooms.