I lost around 60 pounds nine years ago and the main way I keep it off is by eating roughly the same thing every weekday. I've "tuned" it over time to keep me full and avoid overeating and snacking.
Sounds like my story too (lost 25kg about 7yrs ago and kept it off). I generally rotate on a 1-week cycle. The only daily rules I follow are (1) never eat noodles more than once a day, and (2) eat some green vegetable/s once a day. I also never keep food in my apartment to easily avoid snacking, so some days when the weather's bad I'll only eat twice. When I go to an eatery (restaurant or canteen stall), I usually have the same meal every time, but there's about 10 different places I eat at, so I'm making the choice of what to eat when I choose which eatery to go to.
Yeah I developed a stable of foods that I knew the calories of and rotated through those, made my calorie tracking easy.