I was working with a Bambi recently … teaching a new DayZ player how to play the game. It is probably my favorite thing about owning the Evolution servers! I love to teach the game in a non-threatening environment with the amazing community that has come to call these servers "home."
This new player asked an interesting question, and I did not really do a good job answering it in the moment. He asked, "When should I eat? When I am white, but low, or wait until I am yellow?" He was talking of course of his apple icon in the bottom right corner. My answer in the moment was "You get more value for your food if you wait until you are yellow." That is a true statement, but an incomplete answer.
If you are a new spawn trying to loot up and get out of the spawn area, then my advice to you is, if you find food, eat it. The reasoning for this is that when you are usually yellow when you spawn in and have limited storage space. If you are on the Evolution servers, which are PVE, food is plentiful even as you move into the map. You don't want to take up 4 slots carrying around a can of peaches, just eat them.
As you become a little better geared, maybe you have found a backpack or a warmer jacket with more storage but are still fairly new and not far inland from the spawn area, then eat your food anyway unless you are white and full. The reasoning here is that if you can keep your food and hydration up when you are new, you have a better chance of fighting off the dreaded "newbie cold" and to begin building up resistances to the "newbie cold" and other new spawn illnesses. If you are playing on a PVP server, eat your food so that when someone kills you, they don't get your food!
Once you are deeper into the map and your character is more established you probably have some stored food because you got white and full and couldn't eat more when you were new. You notice your apple is dropping, no longer full. Do you eat some stored food now, or wait until your apple hits yellow? Honestly, by this point it makes little difference. You are not as likely to get the new spawn cold now, and you have plenty of food, so it doesn't matter if you get more food value from it. Sometimes I go ahead and eat when the white has dropped, sometimes I don't even notice until I'm red and my tummy is growling.
If by this point you are on an adventure and in a rush with little time, and don't have a lot of food, save it until yellow. If, on the other hand, you are looting up and running out of space, eat some food to clear up backpack space. You can probably hunt by now anyway, so food is abundant.
Here are some other food related tips:
Cook food has more nutritional value, even fruit and mushrooms.
Do not try to dry (or smoke) the fruit and mushrooms as they immediately burn. They will dry naturally in you backpack.
Dried food gives you food value, but no hydration, but it does last longer without spoiling.
Meat goes bad, cook it fast, eat it first, cans can wait.
Honey is the food of all foods! I usually carry a jar and don't touch it unless I am red with no food available. It is my emergency food. Even from flashing red hungry it is hard to eat a whole jar as it fills you up and gives you much nutrition.
Fish is another excellent food source.
I hope this article helps you, and it is factual to the best of my knowledge through current updates. More updates are always on the horizon, so that may change things. If so, I will keep you posted.