She's shed 28 pounds over the past few months, but will she keep it off? That is the question, at least as far as Britney Spears is concerned. The pop diva made an amazing comeback in 2008 -- with her career, personal life and stellar body -- but now sources close to the star are apparently worried she's about to lose her fit figure because she's addicted to junk food.

"Britney's been eating burgers and chips for lunch in complete defiance of the strict eating plan worked out for her," says the source, adding, "It's as if she's trying to defy her father and bosses, and break out of the controlled environment by turning away from the healthy lifestyle they've put in place."

Brit, sweetie, don't do it. Remember the VMA awards? That was pretty bad. You don't need to be super skinny, but at least try to be healthy. (Ditto for the 11 stars featured in the gallery below.)