Bulimia nervosa is a serious psychiatric illness characterised by recurrent binge-eating episodes (the consumption of abnormally large amounts of food in a short period of time), immediately followed by self-induced vomiting, fasting, over-exercising and/or the misuse of laxatives, enemas or diuretics.
Bulimia nervosa differs from binge eating disorder as the binge episodes are associated with a sense of loss of control and are immediately followed by feelings of guilt and shame, which then leads the person to compensatory behaviours — i.e. to immediately purge themselves of the food they just ate.
A person with bulimia nervosa usually maintains an average weight, or may be slightly above or below average weight for their height, which often makes it less recognisable than serious cases of anorexia nervosa.
Many people, including some health professionals, incorrectly assume that a person must be underweight and thin if they have an eating disorder. Because of this, bulimia nervosa is often missed and can go undetected for a long period of time.
Bulimia nervosa often starts with weight-loss dieting. The resulting food deprivation and inadequate nutrition can trigger what is, in effect, a starvation reaction — an overriding urge to eat. Once the person gives in to this urge, the desire to eat is uncontrollable, leading to a substantial binge on whatever food is available (often foods with high fat and sugar content), followed by compensatory behaviours. A repeat of weight-loss dieting often follows, leading to a binge/purge/exercise cycle, which becomes more compulsive and uncontrollable over time.