The Equal Employment Opportunity Commission's lawsuit says the Virginia-based firm that makes military vehicles fired Ronald Kratz II in 2009 for being overweight.
The lawsuit filed in a Houston court says that when the company fired Kratz he was a materials handler who weighed more than 600 pounds. Kratz had worked at the plant in Sealy since 1994.
BAE says it is reviewing the allegations and "will respond at the appropriate time and manner."
The federal agency says Kratz, who received "very good" employee reviews in 2008 and 2009, was replaced by a worker who was not obese.