In answer to a question from far upstream, Kirsten said that after the gang rape she started hooking for drugs. She doesn't know who her daughter's father is. She never mentions it for Neiko but it is implied that she doesn't know who his father is either. She decided to get clean because her drug dealer partner went to jail. I really wonder what that relationship was like since she had only been living with her parents for 8 months at the start of filming.
I particularly enjoyed her phrasing when talking about food. "It's not just keeping me alive like it's supposed to. It's killing me a the same time." So she is a passive victim of food. Late at night the evil food forces itself upon her.
One of the many signs that bode poorly for her long term success, Kirsten explained that after the surgery she can't eat as much as she used to at a given time, but she is hungry more often.