This is called binge eating. They then try to avoid weight gain. Bulimia is thought to be a result of social, psychological, and biological factors. Genetics may contribute. Mood disorders are more common in family members of those who develop bulimia.
Social factors play a major role.
Some societies emphasize thinness. Family problems, self-esteem, and identity conflicts are also factors. Bulimia is most common in females in adolescence or young adulthood. There are no specific ways to prevent bulimia. Promoting good nutrition and self-esteem are important.