Kathy Freston

I missed a tuna-fish sandwich with mayo on toasted wheat bread more than anything. Six months after I went vegan, I snuck into a deli and took one home. And, of course, it wasn't nearly as good as I fantasized. It tasted, well, fishy.

We've all seen chicken portrayed as the low-fat, heart-healthy alternative to red meat for years, but it no longer adds up. You might want to lean away from eating birds and lean toward more plant-based options of protein like black beans, lentils, tofu, chickpeas and whole grains.

Whole foods like grains and beans release their sugar very, very slowly because of the fiber in them, and they don't give you a sugar rush. They feed your cells as needed, and as a result, you have loads of stable energy that powers you through the day.