ive been haveing the same prolem, im in my mid-teens, but ive also lost my appetite via illness, so keep feeling nauseas form not eating enough, even though i eat as much i used to before i started growing!

its like i need to eat twice as much as before, maybe even more, and its perfecty normal, i rmeber the same thing happeneng when iw as 12 or 13, and had a growth spirt, your hunger-level-amouth-whatever will go back to normal within a few months, dont worry :) but do east as much as it wants you to, so you can grow as much as your suposed to~