A 17-year-old girl has height of 172 cm and weight of 40 kg. Nevertheless, she considers herself to be extremely overweight. For the last 2 years she has been keeping to a strict low-caloric diet, while simultaneously working out to exhaustion and tightly binding her waist with a cord. She often self-induccs vomiting. The girl complains of unpleasant sensations in her esophagus and amenorrhea. What is the most likely diagnosis?