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Like braces and Lisa Frank folders, we hoped that pesky breakouts would be something we'd leave in our youth. Unfortunately, even as adults, little blemishes pop up here and there. Why?! To get to the bottom of it, we checked in with Dr. Sharad Paul, a dermatologist and the author of The Genetics of Health, a fascinating book about the connection between our evolutionary past and our future well-being. Here are some potential culprits behind, ugh, those zits and how to remedy them.

RELATED: 6 Ways to Erase Acne Scars (for Real)

what causes adult acne dairy

Your Morning Coffee

If there's dairy milk in it, that is. Dr. Paul cites a 2005 study from Harvard that closely linked dairy consumption to acne—especially skim milk. Luckily, "Cheese did not cause [acne] to the same extent. Nor did yogurt. Possibly because cheese and yogurt are fermented foods," Dr. Paul notes. Switch to nut milk and say hello to clearer skin.

what causes adult acne whey protein

Your Post-Workout Smoothie

Again, only if there's one ingredient present: whey protein. Per research at Brazil's Federal University of Paraíba, drinking whey protein shakes or consuming protein supplements that contain whey can increase acne, since the popular protein is dairy-based. Again, there are lots of plant-based options to still get in your protein, from Herbal Secrets' Pea Protein to Vega's Clean Protein

RELATED: The 5 Best Sheet Masks for Acne-Prone Skin

what causes adult acne stress

Your Job

You know when you're having a particularly stressful week and all of a sudden you start breaking out? Seems like a cruel joke, but it's actually just science. According to a study from Wake Forest University's School of Medicine, emotional stress can worsen or even cause breakouts. Dr. Paul emphasizes the importance of having stress-relieving methods that work for you. Yoga, meditation, staring at pictures of Chris Hemsworth, whatever....

what causes adult acne no fish

Your Picky Diet

We already know we we shouldn't consume as much dairy or whey protein, but what should we be eating more of? Fish. (Calling all anti-sushers: You may want to get on board.) According to Dr. Paul, a study from Italy's Centro Studi GISED found that eating more fish reduces the risk of adult acne. He notes: This is probably due to the beneficial effects of fish oil in reducing inflammation.

what causes adult acne sugar

Your Sugar Habit

This one's a real bummer for anyone with a sweet tooth. A recent Italian study showed an association between acne and a high-glycemic-load diet, meaning a diet "with sugary things like Coke, cookies and cupcakes," Dr. Paul adds. Pour one out for your late-night candy the name of clear skin.

RELATED: 7 Adult Acne Myths to (Ahem) Clear Up

what causes adult acne weight

Your Weight

The same researchers that linked excess sugar consumption to acne also found that, for women, having a higher BMI (body mass index) can mean more adult breakouts. Reason being, women with higher BMIs are at a greater risk for polycystic ovary syndrome (PCOS), which Dr. Paul notes can cause hormone changes that can contribute to acne. "However," Dr. Paul adds, "even in the absence of a hormonal condition, a high BMI can worsen acne." All the more reason to give that sushi a try.

what causes adult acne smoking

Your Smoking Habit

We really (really) hope you don't smoke, but if you do, consider this yet another reason to quit. A study from Rome's San Gallicano Dermatological Institute found a clear correlation between smoking and adult acne. Seriously, for all the reasons, just stop. You T-zone will thank you.

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