I'm a lawyer -- everything's negotiable!
Seriously though -- No processed foods and no gluten (or gluten-free junk foods). Other than that, I eat a variety of whole foods -- as much of them locally (and ethically) grown as possible, particularly animal products (meat, dairy, eggs).
I do watch my calories, but otherwise don't restrict for either carbs or fat (I'm not as healthy when I restrict either one too much, and have MORE trouble controlling my weight, not less).
We're lucky to have a number of very good farmer's markets here in DC -- there are three within walking distance of my house, including one (in DuPont Circle) that runs year-round every Sunday. I've actually met and talked to the people who grow/raise 80% or more of our food. And there's always Whole Foods when I can't make it to market -- but that's pretty much a weekend ritual for us now.