It was a little-known fact that Edward Elric was ripped.
Yes, the Fullmetal Alchemist was quite built for a 15-year-old, as Maria Ross had noted in surprise; his compact frame was corded with small, bunched muscles, and his flesh arm, when flexed, displayed an impressive muscle. Every line in his chest and back was defined; he hardly seemed to have any body fat at all. His shoulders (or shoulder, as it were) had already filled out to taper down to a trim waist, equally trim hips, and long legs that one could only imagine were in just as magnificent shape as the rest of the elder Elric brother.
His whole frame, in fact, was surprisingly adult, to the point of leading Lieutenant Colonel Hughes to say that poor Edward was probably doomed to be short his whole life because everything about his physical suggested his body was already approaching full maturity (a comment which earned him a chamber pot to the head).
However, people rarely noticed these things. Edward's clothes effectively hid him, draping his frame in three layers of material. Nor did Edward make a show of it, nor think it anything of particular note—his body was how it was, and that was that. Now if only he could be taller...
It didn't help that he associated with the likes of his monstrous brother and the relatively infamous Major Alex Louis Armstrong (whose penchant for random shirtless posing, while sparkling, could cause entire cities to sweatdrop, collectively). Compared to them, it would be difficult to say Edward was anything but bean-sized—although one would do well to say it well out of his earshot.
But as Maria Ross later noted, perhaps it shouldn't have been so surprising that Fullmetal was so built.
After all...that small body had to keep up with two automail limbs.