Since the turn of the twentieth century, middle-class Americans have considered the thin body--ostensibly the result of self-control and self-discipline--a moral imperative and a symbol of good citizenship. In this thesis, I provide a critical perspective on fat studies by examining the ways in which the field authorizes itself in a society that deems the fat body unhealthy, costly, and immoral. As one potential solution to fat-hatred, fat studies proposes fat-positivity, but I argue that fat-positivity requires an extraordinary act of imagination in which the fat person overcomes what I term the ideology of thinness and subsequently feels good about herself. Importing models of ambivalence from disability studies, I propose ambivalence as an alternative to fat-positivity. I argue that ambivalence is a legitimate response when living in a society that de-values one's embodiment, but ambivalence is undertheorized by fat studies scholars. In Chapter 2, I analyze from a feminist perspective Tweets with the hashtag "feeling fat," tracing the emotion to cultural ambivalence about consumption and consumerism. In Chapter 3, I examine how the genre of the fat memoir authorizes itself during an "obesity epidemic" and what those methods reveal about gendered selfhood. Instead of indicting these Twitter users and fat memoirists for their purported lack of fat-positivity, I emphasize instead the social situations that give rise to these cultural forms. I suggest that drawing attention to ambivalence is a form of political resistance.