be a meal in itself

Of a food item, to be so filling or rich that one does not need anything else to eat. Typically said of snacks, appetizers, or side dishes. Wow, that appetizer was like a meal in itself. How on earth am I going to have room for the main course? We've created a protein bar so packed with energy that it is basically a meal in itself. That triple-decker sundae is basically a meal in itself, so why don't we split it between the three of us?