random heresy of the day
That may seem like a really obvious question but if your answer is "of course: look at them" let's chat. First of all, visible low weight is an end-stage symptom and patients may not appear thin even when floridly mentally ill. No amount of weight loss satisfies or relieves the desire: in fact the reverse is more common.
(Worth noting here that many patients don't even report being interested in weight loss before being tutored in the language of eating disorders during treatment. See "effort after meaning")
I'm willing to bet that while the desire to be thin is ubiquitous the difference between the anorexic and the non-anorexic isn't the depth of desire but a different way the brain processes disgust and restraint and reward. What seems to be the "reason" to lose weight may not be different than everyone else who starts dieting or purging, and may not be stronger. We get confused by the "success" and assume a greater motivation by dint of the results. Anorexia makes it possible to continue to refuse food and to continue exercising despite energy imbalance: that's not "available" for most people, thank goodness.
Treatment that focuses on that motivation, and advocacy on decreasing that motivation, what evidence do we have that it helps? I'm deeply skeptical. Feels like guarding the well while ignoring the river.
Now the corollary: do people with binge eating disorder want to be larger than other people? Funny: you're probably struggling more with that one.