The sensible answer is to abandon all thoughts of 'three square meals a day' while you are working shifts.
Have several smaller 'meals' that are healthy and nutritious throughout the day, with one 'proper' meal that is smaller than you would normally have.
So, you could start your day with a medium bowl of cereal, and a couple of hours later, a slice of toast or a banana.
Then half of what you would normally have as a sandwich three hours of so after that. Your proper meal later on, and if you would normally have a pudding, have it two or three hours later.
This sort of eating pattern should stop you feeling hungry so you don't eat rubbish and give you the energy your body needs to keep going, without overloading your already stressed digestive system.
Of course, the pattern I've laid out would not suit every day, but gives on idea of how you could think about your meals.
By the way, when you are on shifts, a bowl of cereal, preferably with warm milk, is ideal at your bedtime, whatever time of day that is.