It is vital to have an emergency supply of food on hand in case you cannot be where your food is, so maybe you are stuck late at work, or are stuck out of the house longer than you thought, there are many things that can happen. You should carry these staples in your car and keep them in your office as they will get your though any emergency.
I always have these things in my office RTD (Ready to Drink) meal replacement drink, I like Myoplex Lite Chocolate Fudge Myoplex Lite Peanut Caramel Crisp Bar Can of tuna Bag of instant oatmeal Whey protein Microwave Brown Rice Raw Almonds Rice Cakes Peanut Butter
I carry a few of these items in my car in case I get stuck.
The biggest issue with not having an emergency supply is that you will get hungry and then eat the very first thing you can, and this is usually not healthy food and you will probably eat too much of it because you are so hungry that the fact you have eaten won't even have time to register in your brain.
Now you don't have to keep a huge tub of protein powder in your office or car, you can put some in an old jar or Tupperware container and leave the tub at home.
You can always find water (you had better have a huge bottle with you at all times), so you can mix the oatmeal and whey protein with water and you have a complete meal.
You can eat the tuna from the can (you can buy pull top tuna cans) or put it on rice cakes.
I like to mix tuna and rice together for a "tuna casserole".
There are several combinations here of healthy, perfectly balanced meals. I save the RTD and the bars as a last resort, I prefer to eat whole food instead of drinking it and no matter what is in (or not in) those bars, they are never as healthy as real food.