Bad oils and heavily proceed stuff could be ones to consider. The four main things I try to avoid are dairy, sugar, bad oils (good ones are okay like omega-3 oils, cod, coconut, extra virgin olive oil, almond oil & you can just google em there are tons) & basically anything really "junk foody" that's been heavily proceed. I know in the medical world they say it doesn't matter what you eat but personally think otherwise because I have seen a difference in my skin when I cut out most junk food like pizza, chips, pop & candy. A real reason thats listed for what cause acne is hormonal changes so I'm willing to bet theres a connection between what you eat and how it affects your hormones. Maybe in the future there will be more info on this, maybe a connection. Dairy makes the most sense since they give cows in the commercial industry growth hormones.

This is all just personal experience though and none of what I'm saying is proven fact but in my ownexperience I found when I mostly avoided these four things I never really had any masses break outs come out of no where.Take note of what you eat and how your skin is looks at the end of the day to the next morning, that's how I find if certain foods give me a bad day.
Lastly drink lots of water, enough so that your urine is mostly light yellow to clear. Drinking lots of water alone has really helped out my complexion. Oh and avoid letting anything or anyone touch your face. Hope something here helps you out. Good luck!

New acne stopped erupting after I went dairy free, but it didn't get rid of the acne I already had. It's one of many things that can cause acne. I actually bought a book called Conquer Acne Naturally: The Complete Guide to Clear Skinand the advice in that book really helped solve my acne problems. It's also a very short read, unlike many other authors who write long books without getting to the point.

I believe soy/soya is also bad for acne...