You are what you eat
I personally assume that the "food" here is more about things we put into ourselves, such as what we see, what we think, or what we feel. Just everything we put into ourselves.
So, if this world was a restaurant, everything you can see, think, and feel in this world would be the foods. And the main role here is you! Because you would be the customer in the restaurant who choose the foods you want to eat.
Whatever you eat, it will always affect your body (your life).
That's why it's really important to choose "what you eat", because it's what really shapes you in the end. If you want your life to be better, you should manage what you eat. You can't just consume whatever you see, because not everything you see is good for you. Some foods are good for our health, some are not. Choose them!
The "foods" here are not always from outside. It's not just about what you see, such as the circumstances, things, or people around you. Sometimes it's inside you, such as what you think and what you feel. All these three (what you see, what you think, and what you feel) are the things that in the end will significantly affect and shape who you will be.
The truth is, the restaurant will offer you all the foods. They will not order for you. It's you as the consumer to decide which is good for you, and which is not. When you know it's not good for you, don't eat!
Beware in choosing what you consume, because it is what really shapes who you are. "Eat" good things, and have a good life!