gym rat

One who spends entirely too much time partaking in muscle building, strength training, cardiovascular, or aerobic activity. Specifically, one who does so at a health club or gym. Often used derrogatorily by people who do not partake in or understand this lifestyle, some self-proclaimed gym rats use the term as a status symbol or for positive reinforcement. Rare: The term is sometimes used with homosexual or dim-witted connotations, but both are entirely unfounded (the author of this definition is a gym rat, and does not fit these connotations).