At age 13, Debbie was on her way to becoming a first-rate gymnast. She was always short for her age, but she had to fight to keep thin. One day, a judge told Debbie that if she wanted to improve her tumbling, "she should lose some of that baby fat." Debbie took the comment seriously and began a strict diet. She stopped eating fast food and any fat, and she began to weigh her food and count her calories. A few months later, she stopped eating almost completely and survived on an apple and three pieces of toast a day, Debbie also exercised constantly. Even in bed, she'd wake up to do sit-ups. Debbie started wearing more and more clothes because she could never get warm enough. What disorder does Debbie suffer from?​