Fat-free? Oh, go home. We’d rather chew on a dog toy.

Until we got the skinny on the new obsession of the easily obsessed set: the anonymous brownie. Such mystery! There’s no trace of a brand name on the thing — just a cellophane wrapper and a white label that reads a utilitarian, “Fat Free Chocolate Brownie.” We tasted. Then we tried the caramel. We swooned.

Intrepid reporters that we are, we scrambled to find out who is responsible for the sickest brownie in town. The source? A mom-and-pop operation called Lisa’s Gourmet. They keep it on the DL because they want to preserve that homemade vibe, which explains the low-budget packaging and accounts for the insanely good taste.

Best of all, the brownies are around 200 calories each. Golly, you’d think we were obsessed.

Us? Never.

Available at food stores in Manhattan, including Azure, 830 Third Avenue, at 51st Street (212-486-8080); Bagelry, various locations; Corrado Bread & Pastry at Grand Central Market in Grand Central Terminal, Lexington Avenue and 43rd Street (212-599-4321); F3 Fat Free Foods, 770 Second Avenue, at 41st Street (212-953-0100); and Lite Delights, various locations.