The top players at each position according to body mass index:

(Note: Listed weights for ballplayers are often wildly inaccurate. Minimum playing time determined at whim.)

C Corky Miller
1B Prince Fielder
2B Rickie Weeks
3B Pablo Sandoval
SS Hanley Ramirez
LF Dayan Viciedo
CF Chris Heisey
RF Marlon Byrd

SP Bartolo Colon
SP Tommy Hunter
SP Felipe Paulino
SP C.C. Sabathia
RP Jonathan Broxton

And the low BMI All-Stars:

C Travis d'Arnaud
1B Tyler Moore
2B Michael Martinez
3B Pedro Ciriaco
SS Dee Gordon
LF Starling Marte
CF B.J. Upton
RF Ichiro Suzuki

SP Chris Sale
SP Felix Doubront
SP Hisashi Iwakuma
RP Jerry Blevins