A lot of this is mental. It really helps to deliberately shift your identity to match your target weight. Instead of thinking of yourself as a 220 pound person who has forced themselves to 180 through deprivation, you think of yourself as a 180 pound person who eats what a (healthy) 180 pound person would eat. The old lifestyle and food choices are something you have to detach from because they are gone forever. If you don’t do this, you’ll continue to feel as if you’re in a transient space, and that increases the lure of familiar old ways.