People with bulimia nervosa have recurrent episodes of binge eating and once eating has begun they can't control their behaviour anymore. They regularly engage in self-induced vomiting that allows continued eating or termination of the binge. Eating binges are followed by self-criticism and depressed mood, strict dieting or fasting, vigorous exercise or use of diuretics in order to prevent weight gain. Gross overeating may make the stomach burst, and constant vomiting causes dental erosion and glandular swelling in the face. The most effective treatment is cognitive behavioural therapy, and antidepressant drugs are often prescribed. With good treatment 60% to 70% of the patients recover.
Bulimia nervosa was named in 1979. In the 1970s, there was an increase in the number of women with bulimia who were binge-eating and vomiting to retain a very low weight. In the 1980s there were more women with bulimia whose weight was normal, and bulimia in normal-sized women is becoming more common. A multi-impulsive variation on bulimia is emerging which involves self-mutilation, stealing and alcohol/drug-abuse as well as food abuse.
The incidence figures are controversial, with some sources claiming a rise by 1995 to 11.5 per 100,000 women up to age 24, and others claiming a drop over the 10 years up to 1995 to 5.1% of young women. In the USA female college students were on average 1 kg heavier in 1992 than female college students in 1982. Male students' weight changed by less than 1 kg. In 1982, half the women reported binge eating, whereas in 1992 almost none reported it. Despite showing fewer signs of eating disorders, over 70% of the women wanted to lose weight and were dissatisfied with their body.
In the UK, it is estimated that two in every hundred women aged 15-45 have bulimia and 4-5% are partially affected. This means that body weight is normal but periods are mostly scanty and irregular, and she is probably subfertile. Bulimia occurs in women of any age and class. It often starts in the teens, though sufferers may not feel they have a problem until their 20s. In 70% of cases, the onset of bulimia is closely associated with the beginning or end of a first sexual relationship. A third of anorexics and obese women develop bulimia. Bulimia in men of normal weight is extremely rare.
The incidence of bulimia rises with increasing urbanization; it is 6.6 women per 100,000 rural women, and 37.9 per 100,000 urban women.