Discriminating against or terminating an employee because he or she is overweight is generally not unlawful. Weight is not a protected class under Title VII, however, weight can be a characteristic of a medical condition. Thus, in certain situations taking an adverse job action against an employee based on his or weight (too heavy or too thin) can be a violation of the ADA. The Amendments Act to the ADA provides an expansive definition of medical conditions that render a person disabled under the law. An individual must be able to perform the essential functions of his or her job with or without a reasonable accommodation. If a medical condition causes an increase or decrease in weight, but you are still able to perform your job with or with accommodation, an employer’s adverse job action taken against you due to your weight violates the ADA. Make sure your employer understands that you have a medical condition and that you request an accommodation, if necessary.
Read an article on Obesity under the ADA and a recent settlement on this topic.
UPDATE:
It seems the law is trending toward obesity as a disability. In February 2012 a Federal Judge held that severe obesity may be considered a disability. In EEOC v. Resources for Human Development, Inc., No. 10-3322 (E.D.La. Dec. 7, 2011), the employee weighed over 500 pounds at the time of her termination. The ADA does not specifically address obesity. The Court relied on EEOC’s ADA Compliance Manual which states: “being overweight, in and of itself, is not generally an impairment…On the other hand, severe obesity, which has been defined as body weight more than 100% over the norm, is clearly an impairment.” More importantly, the individual does not have to prove his or her obesity was caused by an underlying health condition. Here is an article on the topic: Summary of Obesity as a Disability. Remember: This is only one Court’s interpretation. Other Courts have reached other conclusions.