body-builder (n.)

by 1916 as "one devoted to cultivating fitness and strength," from body (n.) + builder. Used earlier in reference to healthful nutriments and coach-body makers. Related: Body-building (by 1892, perhaps 1881, in the "training for physical strength and fitness" sense, said to have been coined by R. J. Roberts, superintendent of the Boston Y.M.C.A. gymnasium).