One important thing to keep in mind
Another important thing to keep in mind is weather or not you are doing cardio. That will certainly affect your weight gains, especially at your age. Your body will BURN UP everything. Plus give it time, like someone said early, your body is still developing rapidly, some people's bodies respond quicker then others. The fact that your 15 could also be another reason. Not to say that your too young or anything, but I could put money that once your body undergoes those changes in puberty you will blow up.
Another important thing to keep in mind is weather or not you are doing cardio. That will certainly affect your weight gains, especially at your age. Your body will BURN UP everything. Plus give it time, like someone said early, your body is still developing rapidly, some people's bodies respond quicker then others. The fact that your 15 could also be another reason. Not to say that your too young or anything, but I could put money that once your body undergoes those changes in puberty you will blow up.