First off these thoughts you have of "not being sick enough" are actually signs that you are sick. Because most normal people dont want to be sick or feel fake if they aren't sick. For example if someone breaks their arm and needs to go to hospital it is not like they decide "might as well break my fingers as well as i am going to hospital anyway". You say that you are motivated to recover, so why not begin now.... right away and make your stay at hospital shorter. Because one way or another you will need to gain the weight and if you lose weight before going to hospital it means you will have to be there even longer, and that isnt something you should want.
Also you can not know the weight or BMI of other patients, but also the weight or BMI of someone does not define how bad someones eating disorder is or how much they struggle. There are many who are normal weight but struggle several with an eating disorder, weightloss or weight gain (i.e if someone struggles with binge eating) are just symptoms of the eating disorder.
Yyou need to truly decide that you want to recover and to fully recover i.e change your thoughts and your mindset. Because weight gain is just part of recovery, but it is the whole mental aspect you need to change. And if you go into treatment thinking "i am not sick enough, i have not lost enough weight, i am a fake and begin comparing yourself to everyone in treatment" then the chances are that you might not even accept the help you are given and that it wont really matter if you are intreatment or not because you arent fully motivated to recover.
All treatment does is give you support and be the "guard" which you might not have at home i.e the staff will make you eat and rest, which you might not do while you are at home otherwise. But also they might offer therapy and other group activities to help you recover. But recovery comes from the inside and motivation to recover, it is something YOU have to want and it is better to find that motivation before going into treatment because otherwise you will just be there, hate it and hate everyone there and not follow rules and just waste money being there. .But if you are motivation to recover, then you will accept the help given and sooner be back to life.
You are NOT a fake for wanting to recover. I.e it is so easy to begin comparing yourself to others in treatment. I always thought i was so fat while in treatment, i wondered what i was doing there when i was already huge... i wondered why i had to eat the most when i was already the biggest there. Also eventually when i did begin to like the food i ate i felt like such a fake... if i ever did feel hungry before a meal i would feel like such a failure, when you know what.. it is the opposite. If you accept the help YOU are the winner. You are the one who wants life back and is doing your best to be healthy so that you can live life.
Going in and out of hospital is 1) Expensive 2) You are wasting your own life 3) You miss out on so much and 4) Not fun. There seems to be a competition between patients and those who are sick about who has had the most inpatient stays or hospital visits or who has had tube feeding or a wheel chair or the longest stay in hospital. But it is so completely disordered. I mean, i could go to my friends and be like "Hhey.... i've spent atleast 25% of my life in hospital at this point in my life... Yeah, go me i am so sick" (hahahah, just writing that made me cringe). That of course is nothing i would ever do, because being sick is not an achievment. BEING IN HOSPITAL IS NOT AN ACHIEVEMENT. As many who are disordered seem to think.
Realise that one way or another you will gain the weight. So either you can do it at home or in treatment, but it is much better to spend as little time as hospital as you can and instead find the motivation within you to gain the weight and choose healthy and recovery and fight against your eating disorder. Because in the end, eventually you will be home agian and you will have to be able to eat and rest and fight the disordered thoughts. You are not a fake for eating, you are not a fake for gaining weight, you are not a fake for recovering. Just having those thoughts - that you arent sick enough or a fake, are signs that you are sick.
Find your motivation to recover!!!
I have some posts with similar topics which might help you :)
Being admitted as an inpatient
Comparisons between patients
Not sick enough - an eating disorder mentality
Comparison - an ED thing
Coping with recovery and weight gain
I dont have an eating disorder because....
Helpful tips after inpatient care
Motivation to change comes from the inside
You have to want and choose recovery for yourself (TRIGGER warning pictures in this post)
Feeling greedy, fat or lazy in eating disoder recovery
Lies your eating disorder tells you
Things learnt in recovery