This is an interesting thread. There are examples of all kinds of transformations falling into a few different categories.
1) The anorexic girl who, rather than controlling by starving herself, begins weight training and eating for that and grows exponentially. They seem to be the most dramatic because their obsession to control how their bodies look takes them naturally from one extreme to another.
1a) The girl who is not anorexic but is really skinny and wants to become fit and then falls in love with the changes. (This could also be a subset of 4)
2) The formerly overweight who take control by exercising and eating properly. These are less drmatic, because they drop in size, but in some ways are the most admirable.
3) The already fit person who gets into bodybuilding/training just for the love of improving themselves.
4) The normal looking person who marries a bodybuilder and takes it to the next level with them.
All are interesting
Amazing transformation.