How common is overeating after anorexia?

Not in pure anorexia: Individuals with anorexia nervosa generally restrict their food intake in order to reduce their body weight, often to dangerous or life-threatening levels. There is a subset of people with the "Binge Eating/Purging Type" who may also overeat at times (but then purge with self-induced vomiting, diuretic or laxative use, or enemas) but this is not the common situation.