Unhealthy dieting, bingeing or purging may become a way of controlling, expressing or avoiding feelings; which may lead to an eating disorder.
Research has shown that some people are more at risk than others, but we still don`t know the exact reason why some people develop eating disorders and others don`t.
They are not contagious, and your sibling is not “crazy”. Eating disorders are not just a “phase” or “attention seeking”, and they are not all about appearance and weight; they are about much more than food.