Food:

Food: You can go surprisingly long without needing food. People fast, sometimes for days. The rules of threes claims that you can live for about three weeks without food.

If you have food, ration it to make it last much longer than normal.

After water, your biggest immediate nutritional need is sugar. Lack of sugar makes you drowsy and can lead to passing out. After a day or two without carbohydrates, your brain will be adversely effected and your decision making ability drops to the point of being dangerous.

Food:

You want some carried food, even if you plan on foraging in the wild. Or military foraging, which is known to the victims as looting and stealing.