You know the saying "never trust a skinny chef"? Well, I have my own: never trust a dermatologist with bad skin. Sure, it's not exactly the same, but it stands to reason that a smart dermatologist would know how to take good care of their own skin, right?

That's why when I wanted to know how to really, truly keep my skin looking young (preferably without resorting to extremes like these), I asked some top dermatologists. All of them were happy to share their secrets -- and all have gorgeous skin to back up their claims.

Secret no. 1: "I'm a big believer in vitamin C treatments to boost collagen," says Audrey Kunin, M.D., founder of Dermadoctor. She uses SkinCeuticals C E Ferulic, $138 daily and applies it to her face and decollete. "Don't forget your neck, decollete, arms, hands. They really give away your age," she warns.

Secret no. 2: Amy Wechsler, M.D., author of "The Mind-Beauty Connection," protects her skin from free-radical damage by filling up on anti-oxidant rich foods and beverages. "I drink a lot of green tea and eat anti-oxidants in the form of fruits, and a little dark chocolate," she says. "Ingesting anti-oxidants combats the oxidant stress and damage done to cells by aging, stress, smoking and UV rays."

Secret no. 3: Getting rid of sun damage and discoloration is important to Katie Rodan, co-founder of Proactiv and Rodan + Fields Dermatologists. "I do all of the lasers, but topicals do a much better job of evening out the skin tone and they're less expensive," she says. She recommends exfoliation and applying topicals containing hydroquinone all over your whole face, "don't spot treat," she says.

Secret no. 4: "I take vitamin D3 oil," says Kathy Fields, M.D., co-founder of Proactiv and Rodan + Fields Dermatologists. "It's the new E or A." She explains that you can be in the sun all day and not make enough of it (vitamin D has been linked to bone health and cancer risk). According to Fields the American Academy of Dermatologists recommends taking a supplement of 1,000 ius a day. Fields recommends to "get [your vitamin D level] tested to find out where you are," she says, then take a supplement if necessary.

Secret no. 5: "Brush your teeth after you drink coffee, you want to keep your teeth white," says Rodan, who is a fan of Crest Whitestrips, $34." She claims whiter teeth "enhance the appearance of your skin tone."

Secret no. 6: Howard Murad, M.D., founder of Murad, believes in what he calls an "inclusive health approach." "People look at anti-aging and limit it to appearance of skin on the face, but in reality the relationship with everything else [your internal health, stress level, etc.] is connected," he says. "As much as possible I try to eat a plant based diet. I still eat hamburgers and steak, but I try to limit it. And I wear sunscreen and exercise. It's not one thing, it's a lot of things," he says in regards to what his secret to anti-aging is.

Click here to get 10 more anti-aging secrets from top dermatologists!

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• The doctors agree that a healthy diet is key to looking good. Find out if you're eating right for glowing skin here.

• Sometimes skin care can only do so much, that's why I'm glad I've got these makeup tricks to fake a healthy glow.

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