Intrasexual Competition and Other Theories of Eating Restriction

Various forms of disordered eating and unhealthy eating practices, including excessive dieting, vomiting, binging and purging, and diet-motivated drug use, negatively affect and are potentially fatal to millions of individuals. We describe the etiology of disordered eating as well as various hypotheses on this phenomenon, both from traditional, non-evolutionary perspectives and from evolutionary perspectives. In particular, we explore in detail the intrasexual competition hypothesis, which draws on a broad evolutionary theory: intrasexual selection. From this perspective, women are thought to have evolved to compete intrasexually on thinness, which would have indicated youth and nubility in the ancestral past (Abed, 1998). In modern societies, however, an oversaturation of nubile-looking females, both real and virtual, may overstimulate this competitive mechanism, leading to unresolved body image dissatisfaction and eating restriction to the point of ill health. We discuss the theory, research, and implications of intrasexual competition and then provide a consideration of future directions for research on disordered eating.