Skinnygirl Margarita Is Full of Crap ... Says Lawsuit

It ain't just Whole Foods that has an issue with the ingredients in Bethenny Frankel's Skinnygirl Margarita -- now, a class action lawsuit has been filed against the company that owns the brand.

In the suit, filed in federal court in California, Reneta Bonar claims she and many other people have been duped by Beam Global Spirits for making "deceptive statements" on the label of Skinnygirl.

According to the lawsuit, Beam advertises the drink as "all natural" -- and claims it contains no preservatives. But Bonar says it's all BS because the drink contains a preservative called sodium benzoate.

Skinnygirl was recently yanked off the shelves at Whole Foods -- after the market decided the drink was not using all natural ingredients.

Bonar is suing to force Beam to "engage in a corrective advertising campaign" ... and pay unspecified damages.

Beam has issued a statement saying, "In today's litigious society, nothing is surprising. The litigation filed in relation to the labeling of Skinnygirl Margarita is frivolous. We will defend our case vigorously, and we are fully confident we will prevail."