Kirstie Alley is being sued for allegedly lying about how she dumped 100 lbs.
The suit, obtained by TMZ, was filed by a California woman who claims Organic Liaison -- the weight loss product Kirstie hocks online and on QVC -- is not the reason Kirstie dramatically slimmed down.
Plaintiff Marina Abramyan -- who used the product and filed the class action lawsuit -- alleges Kirstie shed the lbs by dancing her ass off on "Dancing with the Stars" and eating an extremely low-calorie diet.
As for Organic Liaison, Abramyan says it's bogus -- just a bunch of calcium and fiber which is not a proven weight-loss product.
Abramyan is suing for unspecified damages.
We contacted Kirstie's rep. So far, no comment.