Mariah Carey sheds 30s pounds - USA Today (blog)

Mariah Carey bravely posed for this "before" picture, back in July.

And today she unveiled her "after" photo as she was officially announced as the new brand ambassador for Jenny (the company is shortening the name to add a more "perky, fun attitude" to the weight-loss program).

Photos:  The Many Looks of Mariah Carey

Carey tells USA TODAY that several weight-loss companies called her about working with them, but when she spoke to the executives at Jenny, "all of whom had their own issues with weight," she felt "a kinship with everybody I spoke with."

She has lost 30 pounds since starting the diet program on July 22, following the April births of twins Roc and Roe.

She won't reveal her weight, but does say she's "between a 4 or a 6" in size.

Meanwhile, Nick Cannon tweeted about his wife: "Wow!"