There is a misconception in California that you can only fire or discriminate if its for work performance; but generally "appearance" discrimination is generally permissible. There is no blanket legal protection in California for those overweight as there are for gender or race. In fact, there was only one state that we could find that had this kind of protection–that is the great State of Michigan. There has been such advocacy for this kind of protection that even the cities of San Francisco and Santa Cruz of California have passed similar ordinances.
Even though there is no blanket protection, for those individuals that are obese, they may have claims under the American Disabilities Act as there may be some underlying disorder (diabetes, hypothyroidism etc.). In fact, the Equal Employment Opportunity Commission (EEOC) has actually considered obesity to be an impairment under the ADA. California is a little more broad in its interpretation as to the definition of disabled under FEHA.
Can You Ask Your Employee to Lose Weight?
If you can not discriminate, can you ask your employees to lose weight? I would question the boss or supervisor that asks their employees to lose weight so directly due to the risk of creating a hostile work environment, but companies in the past have implemented programs to promote weight gain such as providing healthy food choices, gym membership and other wellness programs.
There is a rationale, whether right or wrong, for discriminating the overweight. Healthier employees may bring insurance premiums down, increase productivity and even help create a company image that the employer is seeking.
Bona Fide Occupational Qualification
There are always exceptions to discrimination and many companies have used the Bona Fide Occupational Qualification (BFOQ) to justify such discrimination. One example of BFOQs are mandatory retirement ages for bus drivers and airline pilots, for safety reasons. Further, in advertising, a manufacturer of men's clothing may lawfully advertise for male models. Religious belief may also be considered a BFOQ; for example, a religious school may lawfully require that members of its faculty be members of that denomination, and may lawfully bar from employment anyone who is not a member.