I eat everything and anything though I shouldn't. I mentioned in another thread or two I have a fetish about gaining weight. I've been deliberately gaining. I've put on about 40 lbs in the past 3 years, and want to gain another 30. The part about what I shouldn't eat is the carbs. I am very carb sensitive, and insulin resistant with Metabolic Syndrome. Yes, my weight probably contributes to it. I'm also non-celiac gluten intolerant. I've been on keto, paleo/primal and Weight Watchers but couldn't stick to any of them. When I'm off carbs for a while, I don't get the cravings, and I lose. But eating a lot of carbs fuels my weight gain, which reinforces my desire to gain. If I can break the carb addiction, I'll lose weight and the desire to gain. I become fatphobic. So in the end I believe a keto or primal diet does change brain chemistry.