Middle English weght, from Old English wiht, gewiht "weighing, downward force of a body, physical property of heaviness," from Proto-Germanic *wihti- (source also of Old Norse vætt, Danish vegt, Old Frisian wicht, Middle Dutch gewicht, German Gewicht), from *weg- (see weigh).
By mid-14c. as "piece of metal used on account of its weight" (fishing-weight, etc.). The figurative sense of "burden" is late 14c. In reference to the weights of a clock by 1510s.
By late 14c. as "what one weighs;" to lose weight "get thinner," of persons, is recorded by 1858. Weight Watcher as a trademark name dates from 1960.
The sense of "importance" is by 1520s. To throw (one's) weight around figuratively is by 1922. Weight-training is from 1945. Weight-lifting is from 1885; to lift weights for exercise or muscle development is by 1907; weight-lifter (human) is from 1893.
To pull one's weight was prominent from 1902, a phrase of U.S. President Theodore Roosevelt that caught the attention of political journalists.
The first requisite of a good citizen in this republic of ours is that he shall be able to pull his weight—that he shall not be a mere passenger, but shall do his share in the work that each generation of us finds ready to hand .... [extract from Roosevelt speech at New York Chamber of Commerce, printed in Lincoln (Neb.) Journal Star, Nov., 17, 1902]
The image is from rowing, where it is attested by 1869.
A shade heavy he may be ; but he pulls his weight many times over. So tremendous, indeed, is his muscle, that, if he were to lash out, he would pull the University eight right under water (etc.) [political humor masked as an account of a rowing race, Cheshire Observer, March 20, 1869]
