I meant rewire

I was underweight until I was 12. Then I was on psych meds and gained 130 pounds. I got off all the meds that caused weight gain and now I can go 20 hours without eating and not feel hungry or lightheaded. If I don't eat during the day I still won't eat much at night. Most of the time I struggle to eat 1100 calories. Sometimes I do get hungry though. I think it has to do with environmental situations if that makes sense. I don't gain an ounce though. I eat like 3000 calories once or twice a week and I don't gain anything and then I don't eat much for awhile and I lose 5 pounds in a week or so. I've lost 42 pounds out of the 100 I need to lose. Is it possible I rewired my metabolism from getting off the meds? Or am I just going back to old eating habits?

I am told that going long periods without food lowers your metabolism and if you do it for a long time, it stays slowed. Also am told that by eating enough and frequently along with exercise, the metabolism can speed back up permanently. I haven't seen that in my own eating yet. I did have metabolic testing done after doing Medifast (under 1000 calories a day for months) and it was very slow. I plan to have it re-tested sometime in the next year to see if it speeds back up with regular exercise.