Duke freshman sensation Zion Williamson wasn't always the tank he is today. Listed at 6-foot-7, 285 pounds, the frontrunner to win National Player of the Year was more than 100 pounds lighter when he began high school before a growth spurt came replete with a huge weight gain.

Speaking to GQ this week about the rapid changes his body endured in high school, among other things, Williamson says he was around 6-3, 175 as a freshman. Over the next two years, however, he picked up a few inches -- and one hundred pounds.

"I didn't pick up all this weight until junior year. Freshman year, I was small. I was 6'3", 175—like, I was small. And over the course of about two years I picked up a hundred pounds. I mean, I wouldn't look at myself and go, 'Wow, I'm 250!' I wouldn't know I was 250 until I stepped on the scale, and then I'm like, 'Oh. I'm 250? I don't feel 250. I don't feel slow.' Like, with all that weight just came more athleticism and finding myself able to do new things. People always say you have to grow into your body, but for me, it wasn't even growing into my body—the more weight came, it didn't phase me. It made me faster, stronger. It helped me become a more versatile player."

Williamson's measurables defy logic. He'd be the second-heaviest player on an NBA roster if he were, in fact, on an NBA roster. And yet Williamson flies through the air as gracefully and effortlessly as any player in the league, young or old. The dunks he throws down within games with ease are among the most impressive we saw this past weekend in the NBA's Slam Dunk competition.

When Williamson's listed 285 pounds first came out last summer, there was healthy skepticism among many that it was not a sustainable playing weight for a player of his size and physical profile. Mike Krzyzewski, however, pushed back on that notion after seeing him in practice all summer -- and turns out he was right.

"At that weight or approximately that weight, he moves as fast as anybody, jumps higher than anybody and he's alert," said Krzyzewski. "We're not talking about someone who has excess body fat. This is a kid that's in pretty darn good shape and just has a man's mass. It's more mass and strength than any type of excess weight. I'm not concerned about that. He's done really well."

Williamson is averaging 22.4 points, 9.2 rebounds, 2.3 steals and 1.9 blocks for the No. 1 Blue Devils this season, and is the odds-on favorite to be selected with the No. 1 pick in this summer's NBA Draft.