Becky is excessively concerned that she is becoming fat and restricts her eating to avoid such a consequence. Her BMI is 17. At times, she will sit down with her family and eat a large meal, but immediately afterwards takes several laxatives. Becky most likely has .

Becky probably has bulimia nervosa.

Explanation:

Bulimia nervosa is an eating disorder much like anorexia. This disorder is characterized by a situation where an individual is very concerned about his weight and for this reason restricts the amount of food he consumes. However, in certain situations this individual develops a binge eating, eating large amounts of food. These episodes leave the individual with great remorse because he believes he will gain weight. As a result, the individual adopts inappropriate practices so as not to gain weight. Among these practices can be cited: provoked vomiting, laxative ingestion, safe exercise practice, fasting for long hours, among others.

Becky usually takes laxative after eating a large amount of food, which indicates that she may have bulimia nervosa.

Bulimia nervosa

Explanation:

Bulimia nervosa is a type of eating disorder in which an individual who has an uncontrollable appetite, consume large amount of food within a short time, and later becomes worried about getting fat overweight. In order to compensate for this binge eating and for fear  being overweight, the individual takes laxative to force purging as an assumed way of controlling their weight. People with such eating disorder often have a low BMI below the normal BMI of 18.5.

The case of Becky is closely similar to that of someone having Bulimia nervosa that involves purging.