everything I have read about the body shapes is that the majority of people fall into two characteristics not just one.
I can atess to how difficult it is to put on weight however my body does change when I workout, muscle develops very easily I just dont get heavier.
Been on large diets from nutritionist with no success, doctors put me on a diet with no success. Got to the point where they were worried that I was real sick. One doctor happened to be correct.
"look at your older brother and father, if they were similar sizes to you at your age, then you will probably find they put weight on at the same age and kept putting it on at the same age". He was correct.
so you can say its bullshit all you like but in reality it isnt impossible, but there is merit behind the argument.