If you watched the recent episode of Nightline where chefs talked about weight loss, you may have wondered what svelte chef Nate Appleman of A16 in San Francisco was putting into his oatmeal. "I haven't had a doughnut in two and a half years," he said while stirring up the bowl. That was a mix of banana, plain yogurt and almond butter, he tells us in an e-mail. What kind of oats? Steel-cut at the restaurant, instant at home.