It's not just about what you eat—it's also how you eat that contributes to healthy living. Gayle talks with Dr. Dean Ornish, author of The Spectrum: A Scientifically Proven Program to Feel Better, Live Longer, Lose Weight, and Gain Health, about eating to live a healthier life.

In The Spectrum, Dr. Ornish categorizes food into a spectrum of choices, from the most healthful to the least healthful. Foods are classified not as being "good" or "bad," but rather by how healthy they are.

Dr. Ornish says the idea is to find out where you are on the spectrum and then try to work toward the healthy end of the spectrum, paying attention to your eating habits, exercise and stress levels. "If you have a piece of bacon, it doesn't mean you failed your diet—it just means [you should] eat healthier the next day," Dr. Ornish says. "You can begin by making moderate changes, and if you get it down, that's great."

What matters most is your overall way of eating and living, he says. Typical diets fail because they focus on what you can't eat, Dr. Ornish says. He says his research shows that the healthiest people are the ones that allow themselves some indulgences. "Using willpower to force changes you don't want to make is not sustainable," he says. "Whatever you like, enjoy it. That's the whole idea."