Recurrent episodes of binge eating occur.
A binge episode involves eating, in a discrete period, an amount that is definitely larger than most people would eat in similar circumstances.
There is also a sense of lack of control over eating during the episode.

Recurrent inappropriate compensatory behaviors occur to prevent weight gain, such as vomiting, laxatives, fasting, or excessive exercise.

The binge eating and compensatory behaviors occur at least once a week for 3 months.

Bulimia nervosa usually looks like a painful cycle of binge eating followed by attempts to undo the binge through purging, fasting, overexercise, or other compensatory behaviors. Shame, secrecy, and shape-weight overvaluation are often central to how the illness is experienced.
Binge plus compensation: Both parts matter. The diagnosis requires loss-of-control binge episodes and compensatory behavior afterward.
Frequency threshold: The pattern has to be recurring, not occasional. DSM threshold is at least weekly for 3 months.
Differential: One of the main distinctions is whether the person is currently at significantly low weight, which may shift the frame toward anorexia nervosa.
Clinical focus: Tracks binge, purge, restraint, and shape-weight concerns.

Tracks binge, purge, restraint, and shape-weight concerns.

Structured interview for severity and diagnostic detail.

Among antidepressants, fluoxetine has the clearest diagnosis-specific FDA indication for bulimia nervosa.

Simple Psych

Bulimia Nervosa