When considering Bulimia Nervosa, an episode is characterized by both of the following

Denial of seriousness of low weight and continued use of compensatory methods to purge calories

Eating behaviours in a period of time that is larger than most people would eat in a similar amount of time and, a sense of lack of control over the binging episode

Loss of menstrual cycle for three consecutive months with <85% of ideal body weight

Strict caloric restriction followed by purging behaviours such as laxative use or excessive exercising