EXCLUSIVE: Alison Sweeney Fires Back at 'Internet Trolls' Over Alleged Fake Diet Pill Endorsement

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Alison Sweeney is fighting mad about a company she claims is using her photo to market a diet supplement she says she would never endorse.

"They're Internet trolls, and people need, unfortunately, to be really careful," Sweeney told ET.

WATCH: Alison Sweeney on Her 'Biggest Loser' Replacement Bob Harper

According to the former Biggest Loser host, the company made a fake Instagram post that they claimed was from Sweeney as well as a fictitious article, which contains false quotes that Sweeney never said.

Sweeney told ET that she's sent a cease and desist letter to the company and has hired a legal team that is "getting involved in litigation."

MORE: Jillian Michaels Reveals Why She Left The Biggest Loser

"The bottom line is one of the best things I learned at The Biggest Loser is how important health is and how important it is to eat right and work out," she said. "There are no short cuts."