Sugary things and excess carbs, especially refined carbs. Processed foods. My skin used to be very oily on a "healthy" diet (lots of whole grains, etc), but since eating low carb, whole foods, my skin is very normal, even if I don't wash it in the morning.
Dairy can be a trigger. Cultured or aged dairy isn't as bad. High quality cheese seems to be fine, in moderation.
Too much fiber/anything that irritates my digestive system. This one is huge. Happy tummy, happy skin. If it makes you bloated or causes you pain, don't eat it. Raw brassicas (broccoli, kale, cabbage, etc.) kill my stomach (yes, even though they're "healthy")
Roasted nuts. Only raw is fine for me.
Vegetable oils. If I cheat a little on pretty much any of the above, I usually won't break out anymore, but vegetable oils will get me every time. Soybean, canola, corn, etc.
Most meat, veggies and fruit are safe for me.
Here's the problem I see:
People want to heal their acne through diet and lifestyle. Great. But then they get obsessed only with their skin and not how they FEEL. Physically. Emotionally. What is the quality of your life? It's not directly connected to your flesh, I can tell you that. Then obsess over their food. They hear "diet" and think low-fat, juicing, fasting, cleansing, starving. You're young. Do you really think you have liver failure? Do you really think you need more fiber?
Paleo changed my life. It's the only lifestyle that ever helped me-not just with my skin, but with my life. My happiness. My fitness. It says, "Eat good quality meats. Eat lots of veggies. Eat fruit too. Some nuts. Then go outside. Walk around. See the world. Play with friends. Lift heavy things. Get some sun. Then go sleep, wake up and do it again." What that means to me is to live an enjoyable, happy, dynamic life where I can be the best me for the people I love, not anxious, not angry, not depressed.
Be gentle to your skin, your heart, your tummy, and your life.
Get out there and live.
And also eat bacon.