Been there an done that. 335 to 190 over a year eating about 1800 calories a day. Kept it off well for a few years then the slow slide back up.

When I hit my target weight, I would eat about 2200 calories a day and stay active and it worked well. New job, wife problems and all goes by the wayside!

I did a 8 year climb back to about 303 at my max but hovered around 285-295 for most of the time for the last 6 years.

Weighed myself this morning and I'm at 258

But back to your point.... As you lose weight, your body gets more efficient. Can't recall where I read it but the reality is that even smaller, your bodies metabolism will most likely be slower than someone of your same size who was never larger. That's why weight gain for people that lose a bunch is so hard to maintain. It's a life long battle