(In fact, the first calls for a slenderised body came not from fashion designers but from doctors who attempted to make a medical case for dieting from before the first world war.)Um-hum, it's that easy to say, so why do so many have a problem with that? The medical profession have continually fanned the flame of any intolerance of fatness. They are not its victims.
I detest the pathologization of bodies on general principle, it matters not whether fat or thin. Thin people are entitled to walk about without being defined as "under"weight though I must admit I will use it in reference to that categorization mainly, because pretending its offensive, derogatory or stigmatizing seems a bit rich. I've always recommended that people consider not identifying as "underweight" though. I tend to think, define yourself as what you are, not what you are not.
As usual a wrong headed mindset keeps attacking the wrong targets; hunger, eating, food, bodies. This is the cause of a lot of the problems assigned variously to other things.
Models are professionals, they're paid because they look a certain way. The idea that this tyrannizes women of any age into self abuse and starvation is and has always been nonsense. The roots of anorexia are in attitudes that value thinness as aspirational and at least slimness as a necessary class/identity marker. Body size is framed as a statement of (your) intent.
The size of models reflects and monetizes this underlying value, it doesn't create it. If we didn't wish to objectify thin women as clothes hangers, they would not be deemed so essential to displaying clothes etc.,
This is still taboo. To say, women want to compete to be the slimmest. We aren't forced well, any duress isn't this irresistible. We have to take most of the responsibility for buying into it.
Rather than jumping to condemn, the basis of this desire and the feelings entangled in it should be thoroughly and honestly examined. It would do women good to stop trying to run away from these feelings.