In addition to being delicious, food should nourish the body optimally, says Dr. Andrew Weil. What exactly does that mean? "The nutrients meet the body's needs while at the same time increasing the body's defenses and resistance to disease," he says.

Eating the right balance of carbohydrates, fats, and protein is key -- including foods rich in vitamins, minerals, phytonutrients, and fiber. Weil outlines his philosophy in detail in his most recent book, "Healthy Aging: A Lifelong Guide to Your Physical and Spiritual Well-Being"; his website, healthyaging.com, also explains the approach. The basic elements break down like this:

-Aim for 40 percent to 50 percent of calories from carbohydrates, the majority from less-refined, unprocessed foods with a low to moderate glycemic load (GL). The GL ranks how quickly the body converts food to blood sugar, which can cause greater fluctuations in insulin levels and result in health problems. A low ranking (slow conversion) GL is 1 to 10, and moderate is 11 to 19. (For an index of food rankings, see glycemicindex.com.)

-Get 30 percent of calories from healthy fats, mainly monounsaturated (good sources include avocados, nuts, olive oil, and expeller-pressed, organic canola oil) and omega-3s (try flaxseeds, fortified eggs, walnuts, or fish, such as salmon and sardines).

-Get the remaining 20 percent to 30 percent of calories from lean protein sources, such as fish, reduced-fat dairy products, and beans -- especially soybeans and soy foods.

-Eat a variety of fresh fruits and vegetables, mushrooms, and whole grains to supply your body with the vitamins, minerals, phytonutrients, and fiber it needs.

See Dr. Weil's delicious dinner party menu.