well, your body is going into overdrive changing itself around. im sure it takes alot more energy to convert your body from male > female, or female > male. so, if you were staying stable before, you would need to eat a bit more, unless your metabolism crashes during transition.
im 5'11 stable at 150-155 depending on the day. @ 3000-3200 calories per day and a decently balanced diet. i drop down to 140 sometimes. hoping i can at least put on a couple pounds, or at minimum, stay where i am. im affraid to lose more weight, again.