In this modern world of plastic surgery and overnight remedies, beauty's become quite the controversial concept. However in Hollywood, not everyone's just about ready to go under the knife. For most celebrities, hard work is what keeps them looking good.

From hot yoga and master cleanse to gluten-free diets, here are the best-kept secrets of the fittest, healthiest and most beautiful celebrities today.

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Gwyneth Paltrow

At 42, Gwyneth is fit and fab. Her secret? She's committed to a gluten-free low-carb diet and yoga workout. She starts her morning with a cup of coffee mixed with half-and-half followed by a breakfast smoothie following an hour of exercise. "Doing some cardiovascular exercise everyday is really good for my skin for detoxification and skin tone and color," the actress said. "I do the Tracy Anderson Method, so I dance for an hour."

George Clooney

At 51, the silver fox is still one of Hollywood's major lady killers. It's as if he's only growing more handsome as he ages. One of his secrets? Bikram or hot yoga. At 105-degrees, this is one exercise that strengthens the core and upper body strength. "Everybody has that year in their life when you age a decade," Clooney said in an interview with Diane Sawyer. "But I'll whip it."

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Beyoncé

Queen Bey has the world under her feet, and for good reason. She's looking better than ever before. Her secret? She's living a devout vegan lifestyle and is committed to doing a master cleanse, which is an all-liquid diet of cayenne lemon water. Of course, she lets herself go once in a while, enjoying a cheat day of pizza and wine.


Daniel Dae Kim

With his glowing skin and unwavering looks, it's easy to see the Lost and Hawaii Five-O has everything under the control. While the rest of us are binging on fries and ice cream, he confesses his fish-heavy diet is what keeps him on top of his health game. "I've eaten more ahi tuna and raw seafood in the past few years than I ever have," Kim, 43, told Men's Health. "It's lean protein, not processed-and it's satisfying." Maybe it's time to finally trade in that patty for some tuna.


Jennifer Lopez

The Latina beauty is easily one of the hottest women in the entertainment industry. If your booty is insured, you know you have a good thing going! So how does J.Lo do it? Balance. She says she doesn't party that much and makes sure she eats right and sweats it out. "You got to work out, you got to watch what you eat," the American Idol judge said.


Will Smith

At 44, the Hitch star is still one top of his game! His secret to living the best life is "running and reading." He added that, "The reason reading is so important...[is that] there is no problem you can have that someone hasn't already solved, and wrote about it in a book." You heard it from the Fresh Prince himself, exercise both your mind and body.


Demi Lovato

The singer is fearless in uploading unedited photos of Instagram. If we've got a body that looked as smashing, we wouldn't mind flooding everyone's feed too! She's come a long way from battling her eating disorder and thankfully, she's emerged victorious. Her advice? Work hard at the gym and know what you eat. "I'm on a structured meal plan. I eat four meals and two snacks a day. It's teaching me portion control," she said. So, still in the mood to gobble down that sixth slice of pizza?