Soda contains ingredients that can harm your skin.

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If you had acne as a teen, you probably heard a million times that you should stay away from junk foods like soda and potato chips. And while mom was right that these foods are unhealthy, the relationship between diet and acne is still unclear. According to Amy Wechsler, M.D., a New York-based dermatologist, the origin of acne is more complicated than food. "The root of virtually all acne is genetics, hormones, stress and inflammation," she says.

But that doesn't mean you can drink all the soda you want and have a clear, glowing complexion. "While there is no direct evidence that soda causes pimples, some ingredients may trigger the body to produce acne," says Jody Levine, M.D., assistant clinical instructor of dermatology at Mount Sinai School of Medicine in New York City.

For example, soda is loaded with refined sugar—and eating or drinking high glycemic foods (such as soda) can lead to increases in blood sugar and fat levels. To battle the spikes in blood sugar, the body will then produce more insulin and testosterone, which can lead to skin inflammation and clogged pores, explains Levine.

A recent study found that eating a low-glycemic diet, one full of fruits, vegetables, legumes and whole, unprocessed grains, significantly reduced acne in male patients between the ages of 15 and 25. The study participants also lost weight and increased their insulin sensitivity.

No matter what, it's important to limit your soda intake, says Levine. Most of us drink way too many sugary drinks, from sports drinks to soda: On any given day, half the people in the U.S. consume sugary drinks, and 1 in 4 get at least 200 calories from such drinks [Source: Harvard]. That makes sense given that a typical 20-ounce soda contains 15 to 18 teaspoons of sugar and upwards of 240 calories [Source: Harvard].

To keep your skin healthy (and your waistline from widening), "make sure you eat a balanced diet filled with fruits and veggies and drink lots of water," says Levine. In addition to being calorie-free, water helps keep your body temperature normal, lubricates and cushions your joints, aids in digestion and ultimately, keeps your body healthy [Source: CDC].