well as long as you don't eat too much carbs and fats you can eat whatever junk you like cause all of it will be used up anyway...it's just that when eating junk your portion sizes are much smaller... For breakfast I'd rather have 3/4 cup rice than a tiny piece of cake.
90% of your leaness and bodyparts shape is due to your genetics and has nothing to do with what you eat or how you train... thats why ectos who try to permanently bulk or overfeed to get "bigger" always quickly stop doing it after a while and didnt add any significant mass. Some go on creatine or steroids for the most insecure, but in the end you always get back to your normal maximal and natural status. You cannont reverse what you ve been genetically designed for unless you go the PED way, but once you go this route, it works only for a while, not in the long term.
Just do the best you can with what you have as long as it's healthy and make sure it doesnt become an obsessive behavior due to psychological issues ; a wide part of the newcommers arent aware of that fact and often waste a lot of time believing in things that are not true and make no sens. Insecurity is the root of 90% of behaviors.
point is, nature didnt make us all equal to each other, some start life with more, some with less, an it goes the same way when it comes to our bodies.
You cannot achieve the same thing someone with a different body and genetics achieved, period. Unless you go the steroid or hgh way, of course. But once these morons stop injecting crap, they get back to a normal , natural body which doesnt look any better than the body of a iron addict who's natural and is consistant with his training.