It is estimated that 10 million Americans suffer from an eating disorder, with millions more having significant stress or anxiety over weight related issues. Eating disorders cover a range of illnesses, from anorexia nervosa (a person being dangerously underweight and still believing they're overweight), bulimia nervosa (a normal weight person who tries to control binge eating by purging food after they've eaten it) and binge-eating disorder (eating large amounts of food due to stress or anxiety) among others.
People with these disorders are unable to change their behavior despite suffering the negative health consequences that result from being dangerously underweight, morbidly obese, or purging behaviors. Patients are overwhelmingly women, but men make up about 10% of patients as well.
Treatment for all eating disorders involves psychotherapy and learning healthy behaviors, and in the case of bulimia and binge eating disorder, anti-depressant medications (Prozac, Zoloft, Lexapro, Paxil, Celexa) have been shown to help as well.