Former “Biggest Loser” star Tara Costa could be lightening her wallet if a lawsuit over her alleged post-show weight gain succeeds.

Costa almost won the reality competition show four years ago by dropping 155 pounds. Her dramatic weight loss earned her a spokesperson deal with FC Online Marketing, which hired her to promote its website ilovekickboxing.com.

The company's CEO, Michael Parrella, told Newsday that Costa was supposed to visit 15 of the company's franchise locations, but that she ultimately didn't go to any appearances because she had gained “in [Parrella's] opinion, about 45 pounds.”

The company is suing Costa for allegedly breaking the fitness clause of her contract by gaining weight, failing to meet her social-media obligations and signing a deal with another gym franchise while still under contract to FC.

Costa denies the alleged weight gain, claiming in a Tweet that during the time when she was supposedly packing on the pounds she was actually completing the Ironman triathlon. She has filed her own lawsuit accusing FC of failing to pay her appearance fees and using her name and likeness without authorization on ilovekickboxing.com.

For more weight loss stories on InsideCounsel, see: