Politeness dictates that you never ask a woman her weight -- but apparently there are no laws against firing her for refusing to reveal it.
Consider the case of Lisa Bonifas, a public library circulation clerk in the city of Urbandale, Iowa. According to the Des Moines Register, Bonifas received a 10.55 out of 12 on her most recent review June 23, but was fired July 26 for refusing to tell her employer her weight. Why was the city asking in the first place? It's printing the information on new city ID cards. 
The U.S. Equal Employment Opportunity Commission says employers asking about weight does not break any state or federal law, though it discourages their doing so unless it's job-related. One caveat on asking about weight: If you discriminate on the basis of the information, you may be violating the Americans With Disabilities Act, which includes obesity. Bonifas is not overweight.
"It's more of a principle thing," Bonifas, 37, told Iowa's Channel 5 TV. "I mean, how much can an employer ask?" 
The city began asking employees for the personal information in July. (Adding blood type and other personal information was optional.) Bonifas declined, and was suspended without pay for one day, and then for three. On July 26, she was fired for "willfully choosing not to comply with the City's ID card requirements," according to her letter of termination.
Jennifer Hubbard, Urbandale's human resources director, told the Register that including height and weight was recommended by the city's police department, which was following FEMA recommendations. The information is intended to help identify employees "in the case of unforeseen disaster," she said – and refusing to reveal the number can be considered insubordination.
For the record, Iowa is one of nearly a dozen states that does not require weight on drivers' licenses – the state removed the requirement because so many people lied about it.
Bonifas says the city's asking is an invasion of privacy, and that in objecting, she wanted a reasonable explanation. Now she's hunting for a job in the insurance industry, where she worked before joining the library two years ago.
Was taking a stand on privacy worth losing her job? "I would have to say yes," Bonifas told the TV station. She says if she could do it again, she'd still refuse to give the city the information "just because I think it's wrong."