Kendra Wilkinson is shrinking fast.

Hugh Hefner's former Playboy Playmate girlfriend dropped down to a size zero while competing on "Dancing with the Stars" this season -- and she says she's still getting smaller.

"I was a size 2 or 4 before 'Dancing with the Stars,' and now I'm a size 0. My waist is still shrinking!" the 25-year-old told Life & Style.

SODAHEAD SLIDESHOW: See the celebrities who could stand to gain some weight.

"When you work out, you produce so much lactic acid, so my body always looks thicker and more muscular. Now that I've had a couple of weeks off, my body is fuller and looks better. I hope I'll look like this forever."

Wilkinson doesn't look TOO skinny yet ... but if she keeps at it, she may be asking for trouble. From LeAnn Rimes to Renee Zellweger to Kate Middleton, let us know: Which celeb needs to gain some weight?