I know this post is from almost 6 years ago, but I figured others might have the same question and could find my answer useful. I have been clean since March 10, 2022, from Adderall, and my weight did not fluctuate at all. I had a monthly prescription of 60mg IR a day and would blow through it in the first two weeks of the month. I would spend the next two weeks recovering by heavily smoking weed and sleeping as much as I could. On my worst days, I would take 200+ mg and would've taken even more if I had enough pills.
A big part of my using was because I was obsessed with being skinny. I stayed in active addiction for longer than I needed to because I had such a genuine fear of gaining any sort of weight. My mind was so twisted that I thought it was worth being an addict if I stayed skinny. My turning point came when I looked in the mirror and realized I was never going to be my goal weight of 99 pounds. I didn't quit immediately after that realization, but it stuck in my mind that even after so many years of abusing Adderall, I STILL couldn't reach the ridiculous goal weight I had set for myself.
When I got clean, I almost immediately started going to the gym because I knew weight gain would be a huge relapse trigger. I started by doing 12-3-30 (12 incline, 3 speed for 30 minutes) on the treadmill. I have eventually worked my way up to using the Peloton app and try to go to the gym 4–5 times a week.
I used to previously try to starve myself or eat as little as I could when on Adderall, and then would binge when I ran out. I was very concerned that I wouldn't be able to eat "normally" and that I would gain a ton of weight after I quit. I now eat three meals a day and snack occasionally, but all in all, I feel like I eat pretty "normally." I don't restrict myself, but I also try not to overdo it with foods that I know aren't healthy.
I don't weigh myself because it's too triggering, but I know that I've pretty much stayed the same weight because I haven't had to buy new clothes. If anything, I have actually started getting a size small shirt instead of a medium. The combination of going to the gym, walking as much as possible, and eating a balanced diet has really helped in my recovery.