The myth about set point weight. (Body composition)

I see in many exercise blogs (written by quasi-recovered anorectics or some who is restricting) that there is a wish and a misunderstanding that the set point weight can be almost bodyfat-free by using strength training and strict diet to exchange the fat-tissue to muscles so muscles take up most of the space under the skin, and fat very little. This must be wrong. It is not the number on the scale it self  the body has in "mind", but the size every organ should have to function best. We need body fat, and to exchange fat to muscles is not healthy or natural. To do so you have to worry about diet. You have to restrict. You can't go from anorexia recovery to strength training and controlled diet and say you still are recovered (and not fallen down to quasi-recovery). I think the body knows how many procent it needs of the fat organ to protect the inner organs and produce enough hormones. The "healthy" exercise culture is pretty disordered, I'm afraid.