Eat real food. Meat, eggs, vegetables, nuts, seeds, fruit, oils (like EVOO or coconut). Eat foods with very few ingredients, all pronounceable ingredients, or better yet, no ingredients listed at all because they’re fresh and natural.
Do not eat dairy. This includes butter, cheese, yogurt and milk (including cream in your coffee).
Do not eat grains. This includes bread, rice, pasta, corn (NOT a vegetable), oatmeal, and also any gluten-free pseudo-grains (quinoa, etc).
Do not eat legumes. This includes beans of all kinds, lentils, and peanuts. No peanut butter!
Do not eat sugars of any kind, real or artificial. No maple syrup, honey, agave nectar, Splenda, Truvia
Do not eat processed foods. This includes protein shakes, processed bars like Zone and Balance bars, dairy-free creamers, etc.
Do not drink alcohol, in any form. If you must drink, try tequila.
My personal principle: Food is on a spectrum of bad-for-you to great-for-you. Make good choices so you can stick with it! Better to "cheat" with some hummus than some really processed junk.