I get this question a lot, and I figure it's time to get an answer down on paper (or rather, screen). My hope is that I can help you recover, and in the process you may or may not gain weight. It really depends on your unique situation. So, while I may have some educated guesses about what might happen with your weight, I cannot determine the future, and I cannot make "ensuring weight maintenance" a goal.
Here are some reasons why:
1. If making sure you don't gain weight means you can't eat enough to fulfill your body's nutrient requirements and energy needs, then you won't be able to recover. You can't recover while restricting.
2. If you feel you can't survive without maintaining a certain weight, then the fear is what we need to work on, not the weight. Recovery means doing the scary work of letting go of an unhealthy coping mechanism. If we don't address that, we're missing the point. You can't be free in a cage.
3. We can't actually control weight. Our eating and activity may influence our weight, but we cannot control it. Weight is largely determined by genetics and it naturally shifts over time. Trying to control something that isn't meant to be controlled not only drains a huge amount of energy, it also distracts us from what really matters. Recovery is about reclaiming your life, not shrinking it to a set of numbers.
4. I do not want to collude with your eating disorder. Your eating disorder is telling you that your worth is all tied up with your weight. I believe otherwise. Your eating disorder might tell you that your value is in your size and that being thin makes you special, but all it does is make you the same as every other person your size. You are valuable because you exist, and the things that make you special are not things that can be weighed on a scale.
5. I don't want you to miss out on learning to be courageous. Becoming ok with your healthy body in a world that is obsessed with dieting and thinness is a real challenge. Even if your healthy body is a thin one, the language of dieting is so universal that it can be hard to feel left out because you aren't dieting. It takes courage to do what is right for you when that thing feels so different. And courage is what's going to get you through this eating disorder and help you cope well in life, wherever life takes you. I want you to learn that you can do hard things and that your life will be better when you conquer your fears and respect your uniqueness.
I want true recovery for you, and that is why I will try to help you recover on YOUR terms, not your eating disorder's.