Here is a statement from her blog http://juliasweeney.com/october-11-2013/
One interesting thing I learned was this: negative self-talk backfires. There is no upside to negative self-talk. Your brain hears yourself tell yourself shitty things about yourself and it reacts to it as if it were another person saying those things. Then it (you) look (subconsciously for the most part) for rewards to make yourself feel better about yourself. That’s why, when someone berates themselves for being fat, for example, they end up eating an ice cream sundae a few hours later. I mean, if your way to reward yourself is with food. But it applies to anything.
Julia Sweeney is the author/presenter of Letting Go of God, a sensitive and funny statement of atheism. Sweeney is a professional comedienne and an ex member of Sat. Night Live. McGonigal is indeed a prof. at Stanford and her book and her interview on To The Best of Our Knowledge are very good. Interestingly, she is the very twin sister of Jane McGonigal, a well-known author and authority on video and other games.