gainer

noun3

1. •
   One who gains a profit or advantage.

   • … it is obvious that the Californian heiress is not the only gainer by an alliance which will enable her to make the easy and common transition from a Republican lady to a British peeress. — 1892
2. •
   A diving or gymnastics maneuver, from a high diving board or platform, involving a simultaneous inversion and rotation.

   • I tried a full gainer with a twist, the way he did it, but succeeded only in smacking the water with my thighs. — 1961
3. •
   One who puts on weight.