Are fad diets borderline eating disorders?

I’ve seen people go through various fad diets and I’m surprised how accepted it has become to do these diets.

I’m talking about the “30 day cleanses” and the highly restrictive diets. The diets that have you survive on a liquid diet or “tricking” your body into starvation mode which will make you shed a ton of weight in no time, etc. Stop eating food and just drink this shake.

From what I’ve seen, the fad diet culture encourages an unhealthy relationship with food. Maybe even leads people into eating disorders.

Usually it’s the same people cycling through the fad diets as the new one gains popularity.

So, are fad diets harmless or borderline eating disorders?