Doesn't look like a steroid body at all.

Very low body-fat is all, heavy endurance conditioning will do that.
And Tim needs it the way he fights. Fantastic conditioning, he keeps coming on.

Not many guys have that kind of endurance. Bradley, Pacquiao.
Joe Calzaghe had it. Margarito. There's only a handful can go at that pace.

The late Tommy Morrison was on steroids, and despite 5 mile runs, this guy ran out of gas in 5 rds. He just couldn't develop that kind of conditioning. The Foreman fight is the only one where he showed a gas tank.