Hey, Pizzaface! You’ve heard it before, though it’s long been assumed to be an urban legend: junk food makes your face break out. Growing up, I knew plenty of people who ate whatever they wanted, and had skin like a Dove model’s. I also knew people whose faces looked like the surface of Mars, seemingly no matter what they ate or didn’t eat and despite taking prescription meds that made them act weird (Acutane, for instance). But now, after 30 years of scientists denying a solid connection between diet and pimples, Scientific American is reporting that some fatty foods — particularly dairy — may play a role, but not because the fat in those foods ends up in your pores. Rather, the hormones they contain can trigger testosterone surges in the body, and testosterone is a major contributor to acne outbreaks since it dials up the activity of both the sebaceous glands and the lining cells. Testosterone is also the reason that acne outbreaks tend to be worse in teenage boys than girls, though both sexes are vulnerable.

According to Scientific American, the reason for this is that “milk from pregnant cows contains hormones that oil glands can turn into dihydrotestosterone, testosterone’s most potent form.” Doctors who have asked acne-suffering patients to cut out dairy for six months often find that this change in diet has a dramatic impact on acne. But dairy isn’t the only suspect in this case; researchers also think (but can’t yet prove) that diets high in white flour and processed carbs contribute to acne, and that diets high in “good” fats like Omega-3 can help assuage pimples (”good” fats are anti-inflammatory). When all is said and done, though, it could turn out that pizza — rich in dairy, white flour and processed carbs — really does give you pizza face.