I had Anorexia Nervosa as a teen. I'm male.
My daughter is in recovery from Anorexia Nervosa.
While my daughter was in treatment, I met quite a few adolescents with Anorexia and Bulimia, and their parents.
Some died.
They are called "Eating" disorders, not "weight" disorders. Unless you see a person's eating behaviors, you cannot diagnose them. A person may have an eating disorder without being especially thin (although the specific diagnosis of AN requires "a significantly low body weight"), or they may be especially thin without having an Eating Disorder.
What *is* universal among those with Eating Disorders are painful feelings of shame and inadequacy. Those with Eating Dangerous use dangerous eating behaviors as a way of dealing with their pain, because they've somehow discovered things don't hurt so much when they use the behaviors, at least for a little while.
That's the problem with these threads.
When people judge runner A's appearance harshly because of their weight, it's not runner A I worry about. Runner A is probably not going to see it. I worry about the High School junior who hates what she sees in the mirror each morning. Then she reads threads where people harshly criticize some runner's weight or shape, and next time she looks in the mirror, she hates herself a little more. I worry about the guy who hates himself because he's not thin enough to be good, and he sees people getting criticized for being too "fat". He looks in the mirror or steps on a scale, and he hates who he is even more.
Go ahead. Talk about runner X not running well. But don't go on and on calling them fat. Because that's never the root cause.