n. Muscle dysmorphia; a mental disorder in which patients—typically bodybuilders—think they are physically inadequate.
Bodybuilders and their beautiful sculpted bodies that look chiseled out of fine Italian marble may be suffering from the flip side of anorexia.

Muscle dysmorphia, a newly identified psychiatric disorder gives a bodybuilder the perception of being a 98-pound weakling no matter how cut he or she is.

"Bigorexia's" preoccupation is so powerful that those who suffer from the malady often give up their jobs so they can spend all day at the gym.
—Sharon Robb, “Bodybuilders May Encounter 'Bigorexia',” Sun-Sentinel (Fort Lauderdale, FL), November 30, 1997
Eric Hollander, an associate professor of psychology at Mount Sinai School of Medicine, said that for some men, their size becomes an obsession. He described a phenomenon known as bigorexia, wherein small men abuse steroids or lift weights compulsively in an effort to look larger.
—Carmen R. Thompson, “The lack-of-height report,” Daily News, September 03, 1995
1985 (earliest)
The Barbarian Brothers have a problem, which they have dubbed 'bigorexia.' Explains David, 'It is an obsession like anorexia. We always look at ourselves and ask, 'Do we look big?' We get crazy about looking small.'
—“Take a quarter ton of talent, add a heap of self-promotion, and you have the Barbarian Brothers,” People, August 12, 1985
Neology often isn't much fun for language prescriptivists (people who believe in a "proper" form of the language, and spend great gobs of time trying to reform the linguistically incorrect.) First, they tend not to like change all that much, so they don't take well to most new words. Second, they get positively apoplectic when confronted with a word such a bigorexia with its sloppy etymology. The problem, you see, is that the Greek suffix -orexia means "appetite." So bigorexia means, literally, "big appetite," which isn't even remotely close to the actual meaning. (Although one assumes that those suffering from bigorexia would have to consume large quantities of food.) Descriptivists just shrug and move on with their contented lives.