How can you avoid gaining weight you lost on vyvanse/amphetamines once you stop?aside from suppressing appetite they do increase basal metabolic rate

Rebound weight gain: It is not unusual to experience wight gain after discontinuation of Vyvanse (lisdexamfetamine) or other stimulants due to rebound increase in appetite. If not kept in check, it can lead to weight gain, as would be expected. It does not increase BMR, as is commonly believed. The best way to maintain weight is to monitor calorie intake and activity level. This can be achieved with mindful eating and regular exercise.