Dairy
When you develop cystic breakouts—those hard, painful, underground blemishes that linger for weeks on the chin, jaw line, and neck area—it might be a sign that you’re getting more dairy in your diet than your body can tolerate, says celebrity esthetician Renee Rouleau. Your skin acts as an excretory system to get rid of things that your body doesn’t agree with, so when you take in too much dairy, it comes out in the form of cystic blemishes in the lower area of the face.

Processed Foods
Highly processed junk food made with additives and preservatives—such as white bread, chips, French fries, soda, and candy—makes your blood-sugar levels spike. This causes your hormones to stimulate excessive oil production, clogging pores and aging the skin, says nutrition consultant Carina Sohaili, founder of Vibrant Healthy Life.

Caffeine
Caffeinated drinks dehydrate you, which does a number on your skin’s elasticity and collagen—and that can make your skin more prone to sagging and wrinkles, says Christina Kauffman, owner of the spray tanning salon Blush. If you can’t go without it, make sure to drink the recommended eight glasses of water daily to keep your body and skin hydrated.

Shellfish
Shrimp, crab, and lobster are high in iodine, which can lead to clogged pores and acne. A better option is fish, which contains omega fatty acids that help improve your skin, says Crystal Wellman, owner of the skin-care company Crystal Clear Acne Clinic.