You watch, SM's about to shoot straight up. He's going to be potentially several inches taller by the end of next year. Consider the growing pains, not to mention the hormonal changes, he's going through! I think he's basically a good soul who needs some time and some space to come into himself.
I am not a fan of dishing on children in any capacity, especially when it comes to appearance, but I have to say that this was my first thought too.
I was quite chubby at the exact same age SM is at now, but wasn't within a couple of years. When I hit puberty, I grew "out" before I grew "up" if that makes sense. But when my height growth spurt came along and I went from 4'10 to 5'5 in one school year, it was fine because that weight became pretty evenly distributed over my taller frame (sadly, I'll always have a little tummy pooch, I've accepted I'll never have a flat stomach).
I had one hell of an awkward phase for about 18 months when I was 13/14 and waiting for/going through my growth spurt (it didn't help I was outgrowing a pixie hair cut), and I am so
glad I did not have to live that out in the public eye.