The battle is so unreasonable.
If MC fight twice, they can't fight anymore. They must rest, but when they rest, they consume food and water.
However, there are very few resources you can find in the field, and too often you can't find anything even if you browse the house.
No wood, no metal, no stone, no food, no water. How on earth can you hold on?
- By harvesting fruit from trees, mushrooms, berries for food. And Kate can make a fishing rod if you find what it takes.
- By powering water into the river and then purifying it over the campfire to have drinking water (this can be improved in pump which can be further improved to decrease the time and increase the quantity).
- Find the axe to cut down trees.
- Find the pickaxe to break the stone blocks.
- Food and drinks can also be consumed directly between fights to recover life but do not count towards meals.
- It is possible to find a doctor who will make healing potions more effective than food and drink.
- You can leave a region you are in by following the road to go to other regions. Watch out for the colored lines on the map that indicate areas with stronger zombies and therefore more powerful equipment is needed by upgrading Kate's workshop.
- When there are no zombies in a region, it is possible to find a dead survivor and look in their bag for resources.
- There are also other possibilities with other survivors but you have to find them.
It is not only the search in the ruined houses that it is possible to find all this and this is explained in the introduction and in the GameFaq. Kate even tells you the location of the axe and pickaxe when you recruit her and she also explains the system of the bucket of water in the river.
PS : Normally, there is enough food in 1 region to feed 6 characters for 1 day, not counting the bonuses that some NPCs bring to the base. There is no wood or stone to be found in the ruined houses.
There are so many possibilities that I may forget some so I advise you to go see the GameFaq to read what you didn't see in the explanations in the game.