In survivalist circles, there's a common rule known as the Rule of 3. What the Rule of 3 says is in a worse-case scenario you're dead in 3 minutes without air, 3 hours without shelter, 3 days without water, and 3 weeks without food.
Your Zombie Survival Plan should be centered around the Rule of 3, meaning the first thing you should worry about should not be food. You can survive up to 3 weeks without food. You're dead in 3 days without water. Human beings need a massive amount of water on a near-constant basis to keep ourselves alive.
Air: Hopefully you're not underwater and you're able to breathe. Shelter: You may be in a warm climate, so the actual elements may not be hazardous to you, although they can be very deadly very quickly. You do need to shelter yourself from other zombies, worrying about zombie bites, staying out of sight, staying protected. That should be your first concern after just getting enough air to breathe. Then you need to worry about water. Human beings need a large amount of water on a near-constant basis to stay alive.
Within the notion of the Rule of 3s, you can see that food is the last thing on your list. When crafting your Zombie Survival Plan, you always need to pay attention to the Rule of 3, because if you don't setup your priorities accordingly, you can find yourself dead of dehydration before you even see a zombie.