FILE - In this Oct. 26, 2009 file photo, personal trainer Jillian Michaels speaks at the Women's Conference 2009 Night at the Village at The Long Beach Convention Center in Long Beach, Calif. [Agencies]

LOS ANGELES – Jillian Michaels has been sued for alleged false advertising by a woman who claims she was duped into buying a diet supplement endorsed by the celebrity trainer.

Christie Christensen of Lake Elsinore, Calif., is seeking class-action status for the case she filed Tuesday in Los Angeles. Michaels is a hard-charging, no-nonsense trainer best-known as one of the stars of NBC's hit reality show, "The Biggest Loser."

Christensen's lawsuit claims she bought a product called "Jillian Michaels Maximum Strength Calorie Control" last month and that it has failed to lessen her appetite or cause her to lose weight as advertised.

Michaels' picture and endorsement appear on the packaging, touting her as "America's Toughest Trainer." The product and a Web site advertising include the claim, "Two Capsules Before Main Meals and You Lose Weight ... That's It!"

"Ms. Michaels knows better — taking two pills before eating does not miraculously cause weight loss," the lawsuit states.

The Web site and packaging however note that the statements haven't been approved by the U.S. Food and Drug Administration. Christensen is also suing Utah-based Basic Research and ThinCare International, which manufacture and market several diet and weight loss products endorsed by Michaels.

ThinCare said in a statement it offers a money-back guarantee for purchasers and expects to win the case. The company also touted touted its products' popularity and testing standards.

"Not only have placebo-controlled, double-blind, published clinical studies been conducted on the active calorie-control compound in Jillian Michaels Maximum Strength Calorie Control, but that research was reviewed by some of the leading weight-loss experts in the world before Jillian would put her name on the product," the statement read.

Michaels' publicist, Heidi Krupp, did not return a phone message seeking comment Wednesday.

"Calorie Control" is not among the products that NBC lists for sale on its "Biggest Loser" Web site, which include video games, DVDs and equipment, some bearing Michaels' image.

"The Biggest Loser" has been a hit for NBC, often appearing in Nielsen Co.'s Top 20 rankings for prime-time TV programs.

Christensen's suit seeks unspecified damages that are not expected to total more than $5 million. Her filing states she has "struggled with weight loss her entire life" and bought "Calorie Control" because of Michaels' endorsement.