Grocery store shelves are packed with foods labeled "Fat-free," "Natural" and "Healthy." They're designed to appeal to the health-conscious shopper. But how can you really tell which foods are good for you, and which ones aren't? We asked a pair of Twin Cities nutrition experts (Professor Joanne Slavin from the U of M and registered dietitian Sharon Lehrman) to help us come up with the right answers. You might be surprised with what we found.