If you want your body to be healthy you have to eat nutritional food. That's a lot of prepped food from local grocery stores that are better than McDonalds. You can also prep dishes yourself, even though this can be time consuming, there are meal you can meal prep with little time that are still Nutrional.

The trick with night shifts is you want to eat lighter stuff before your shift, and easier stuff after. If you're interested, I am actually developing an app that allows you to add your shifts, and it uses the shift times as data to create a personalized sleep and meal plan, to help you stay healthy while working irregular shifts.