I'm pushing 59 this year..... dang.... that came quickly.....
anyway..... I have been in the 150 to 160 lb range all my adult life. Never below and never above. I eat what I want pretty much, when I want, and as much as I want.
I take small portions. You can see the plate between them. And no seconds.... well, maybe the turnip greens my MIL cooks. Low sugar intake, no chemical sweeteners, and no bread... (well again rarely on the bread..homemade is the one exception)
I often leave the table with a bit of hunger remaining. It's a crazy way to live but that's how I do it.
I also stay active. Exercise and simple activity outdoors. Nothing radical.