They also tended to eat more foods with a higher glycemic load, meaning they spike blood sugar more sharply after eating. Foods with a glycemic load of 20 or more are considered high, while those with a glycemic load of 10 or less are considered low. (To learn how to eat to lose fat, check out The Metashred Diet from Men’s Health.)

Complex carbs—which usually contain more fiber—tend to have lower glycemic loads than simple, or refined carbs do, which tend to raise your blood sugar more quickly. So, for instance, a whole wheat tortilla, which has a glycemic load of 8 per serving, would cause less of a blood sugar spike than a white bagel, which has a glycemic load of 25 per serving.

So how might high glycemic load wreck your skin? The researchers believe it could trigger the excessive production of insulin, which also increases your concentrations of a hormone called insulin-like growth factor-1, or IGF-1. Too much IGF-1 can promote a greater release of androgen hormones, which stimulate oil production in your skin—possibly triggering or aggravating acne.