She is so unattractive (morbidly obese) now that nobody will hire her as a principle. 

The movie "Trainwreck" is actually not a bad movie at all. The plot is generally about a promiscuous female reporter for a magazine with "daddy issues" gets involved with a sport's doctor she is interviewing and must face her own insecurities/paranoia about dating normal men instead of engaging in endless one-night-stands (playing the STD lottery). 

Sub plot is her father is in a retirement home and though she loves him, she has to deal with the fact that he is responsible (mostly) for her paranoias about normality and endless alcohol abuse / fornication. 

With an uncle like Chuck-You Schumer it's not necessary to speculate as to the source of the real-life problems of Schumer to wit, her severe overeating problem. She must somehow bury all of the humiliation/horror of what she has become  - an ally of Satan. So the actress Schumer eats constantly just to help her cope. 

It must be hard to be a successful stand-up comedian/comedy actress when you feel depressed most of the time.