If eating disorders, Bulimia nervosa in particular, have evolutionary functions or if they are new modern "lifestyle" problems is still debated. Social
Media portrayals of an ideal body shape are widely considered to be a contributing factor to bulimia. In a 1991 study by Weltzin, Hsu, Pollicle, and Kaye, it was stated that 19% of bulimics undereat, 37% of bulimics eat an average or normal amount of food, and 44% of bulimics overeat. A survey of 15- to 18-year-old high school girls in Nadroga, Fiji, found the self-reported incidence of purging rose from 0% in 1995 (a few weeks after the introduction of television in the province) to 11.3% in 1998. In addition, the suicide rate among people with bulimia nervosa is 7.5 times higher than in the general population.When attempting to decipher the origin of bulimia nervosa in a cognitive context, Christopher Fairburn et al.s cognitive-behavioral model is often considered the golden standard. Fairburn et al.s model discusses the process in which an individual falls into the binge-purge cycle and thus develops bulimia. Fairburn et al. argue that extreme concern with weight and shape coupled with low self-esteem will result in strict, rigid, and inflexible dietary rules. Accordingly, this would lead to unrealistically restricted eating, which may consequently induce an eventual "slip" where the individual commits a minor infraction of the strict and inflexible dietary rules. Moreover, the cognitive distortion due to dichotomous thinking leads the individual to binge.
A lifetime prevalence of 0.5 percent and 0.9 percent for adults and adolescents, respectively, is estimated among the United States population. Bulimia nervosa may affect up to 1% of young women and, after 10 years of diagnosis, half will recover fully, a third will recover partially, and 10–20% will still have symptoms.Adolescents with bulimia nervosa are more likely to have self-imposed perfectionism and compulsivity issues in eating compared to their peers. This means that the high expectations and unrealistic goals that these individuals set for themselves are internally motivated rather than by social views or expectations. Criteria
Bulimia nervosa can be difficult to detect, compared to anorexia nervosa, because bulimics tend to be of average or slightly above average weight. Many bulimics may also engage in significantly disordered eating and exercise patterns without meeting the full diagnostic criteria for bulimia nervosa. Recently, the Diagnostic and Statistical Manual of Mental Disorders was revised, which resulted in the loosening of criteria regarding the diagnoses of bulimia nervosa and anorexia nervosa. The diagnostic criteria utilized by the DSM-5 includes repetitive episodes of binge eating (a discrete episode of overeating during which the individual feels out of control of consumption) compensated for by excessive or inappropriate measures taken to avoid gaining weight. The diagnosis also requires the episodes of compensatory behaviors and binge eating to happen a minimum of once a week for a consistent time period of 3 months.