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If you own stock in Cheetos, you'd better sell lickety-split, because the bottom is about to fall out. Britney Spears, the longtime poster child for the cheesy, curly treats, is apparently doing her best to eat healthy, which might explain the fit and foxy bikini body she was sporting during a Mexican getaway over the weekend.

According to the guy who styled the popster's forthcoming video for her chart-topping single "3," a musical endorsement of threesomes, she showed impressive willpower when a salt craving hit during the shoot.

RELATED: See pics from Britney's bikini-clad hotel party

"She exhibited amazing energy and was in great shape -- her body looked better than it has in years," GK Reid gushes to the New York Post. "She munched on sushi instead of junk food, and even sang live with the words. She worked really hard and was really sweet to all the dancers."

No word on whether Spears has also curbed her Frappuccino habit, but she's obviously doing something right given how toned she looked in her black, South of the Border two-piece (her chronically matted extensions, however, are another story).

But in the current body-obsessed tabloid culture, a star can't win for losing (weight).

RELATED: Check out pics of Britney over the years

Case in point: The London Daily Mail has evidently done a thorough examination of Brit's vacation cleavage and determined that it appears "noticeably less curvy" and "deflated."

But before you alert the mammary police about her seemingly "fast-disappearing" cup sizes (or smack your head on your desk over the intense scrutiny that female stars are under), keep in mind that the back-on-track but still-under-supervision singer was wearing a bikini top with a little more frontal coverage than she typically favors.

Spears, 27, who is on a breather from her Circus tour before heading Down Under for several planned dates next month, was soaking up the rays at a resort in Zihuatanejo (also known as the tropical paradise from "Shawshank Redemption") with sons Sean Preston, 4, and Jayden James, 3.

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Also along on the Mexican jaunt: her dad, Jamie, a nanny, and her manager-cum-sometime boyfriend, Jason Trawick, who has been a near constant presence in recent weeks.

Meanwhile, it turns out Brit's ears might have been burning right along with her epidermis. Seems her name came up during a lecture Jack White gave at Trinity College in Dublin over the weekend.

Among the topics covered: his philosophy on rock 'n' roll authenticity.

"I don't know if Bob Dylan and Tom Waits are as authentic as I think they are. Perhaps they're not," the White Stripes front man noted (via NME). "Sometimes you start thinking that maybe Britney Spears or someone like that who's doing exactly what they want to do in the way that they best know how, is more authentic than any of those people you could mention."

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