Fear of rejection is part of an ED, but don't forget fear of humiliation that goes hand in hand with it.
From humiliation comes anger, but to take it out on the one(s) who humiliated us is fruitless so where do we direct it? The body that also was a part of why the humiliation happened in the first place. We can not control other people, but we can try to prevent it from happening again. Hence making us look child-like, innocent, pretty or cool so people will less likely think of attacking us again. Every time I felt humiliated I looked at myself from the outside and I saw what I felt; big. Humiliation feels like exposure, enlarged under a magnifying glass and scrutinised. We don't want this humiliation to happen again. We also want to heal from the experiences, but we don't know how to do any of those things so we reduce our own body. We simply don't know better and those who were suppose to take care of us did not either.
I can give you two examples from my own life. My dad left me when I was 10 and when he came back to see me 6 years later he just stood in the other end of the living room and looked at me. He did not come to hug me and said nothing. Just looked at me for a long time. It was uncomfortable. I felt exposed. Then he said: You have grown. He did not look happy. I thought he was unhappy with how my body had turned out. I felt rejected. He did not come closer, he said nothing more. Yes, so I felt humiliated, exposed, scrutinised. (My dad was a weird man. He never hugged me, held me, I never got to hold his hand even when I asked him to. My mum never touched me either. Not even when I had hurt myself did she try to calm me down by touching me a little. )
Another time I felt humiliated was when a 44 year old man exposed himself to me when I was 16. He had sat his chair into the hallway where he knew I would come before bedtime so I could see him when I passed by. There he sat with an open dressing gown and his hand on his penis, sleeping. I thought God was behind this, showing me myself from the outside, so when I went into the bathroom and saw myself in the mirror I saw a fat pig there instead.
That is when I started restricting food. First pig meat. The woman in the house thought I was dieting when I said I didn't want the pork dinner she served me and suggested I avoided bread with cheese instead. So I did. And thought I should go on a restrictive diet since she thought I was dieting. She would never think that unless I needed it, I thought.