Why are dumbbells called dumbbells?

The term "dumbbell" developed in 17th century England, and it was inspired by the clappers (the weighted, swinging part of the bell) of large church bells. Since the clappers on these bells were heavy, bell-ringers would often train using weighted but soundless—hence "dumb"—clappers to build strength. The term "dumbbell" soon caught on to describe these soundless clappers. At a later date, strongmen and athletes began adding weight to the other ends of clappers for the purpose of strength training, and they kept the dumbbell name. Even though the styles and materials of dumbbells have changed through the centuries, the clapper-inspired name has persisted.

Why do we weigh less in the morning?

A common, erroneous explanation for why we weigh less in the morning is that the undigested food eaten throughout the day is absorbed into the body during sleep. The problem with this theory is that it fails to explain where the mass goes; once a meal is digested, it is still in the body. The correct explanation is that we lose water weight through breathing and sweating. Also, we constantly breathe out carbon dioxide, and the mass from the released carbon adds up throughout the night. A combination of breathing, sweating, and releasing carbon, therefore, makes us lighter in the morning.