What Matters Most: Diet or Exercise?

For losing weight, fighting disease,
and boosting overall well-being.

Losing Weight:  The winner - Diet
The reason: As research makes clear, trimming calories from your diet is the most direct route to a smaller dress size. "It's much easier to cut 500 calories than to spend an hour in the gym burning 500 calories every day," says Timothy Church, M.D., Ph.D., director of preventive medicine research at the Pennington Biomedical Research Center at Louisiana State University. However, both diet and exercise are essential for keeping that weight off.

Boost Energy: The winner - Exercise

The reason: Exercise causes the brain to pour out invigorating neurotransmitters like dopamine and norepinephrine, says Patrick O'Connor, Ph.D., an exercise psychologist at the University of Georgia. People who train consistently report surges in energy, according to some 70 studies.

Reduce Risk of Heart Disease: The winner - Diet

The reason: "If you had to focus on one nutrient that would lower your heart disease risk, it would be omega-3 fatty acids," says William Harris, Ph.D., director of the cardiovascular health research center at the University of South Dakota. In studies, omega-3s from oily fish lower heart disease risk by up to 64 percent. That said, working out does strengthen your cardiovascular system.

Prevent Diabetes: The winner - Exercise

The reason: Nearly 10 million American women have diabetes. Achieving a healthy weight through diet and exercise is the strongest defense against the disease, but physical activity has a slight edge. Active muscles gobble up glucose from the blood for fuel, which helps keep blood-sugar levels stable.

Prevent Cancer: The winner - Both
The reason: Eating a mostly plant-based diet and exercising regularly remain the gold standard for warding off cancer. Keep in mind: Studies have found the more consistently you work out, the greater the protection.

Improve Mood: The winner - Exercise

The reason: A 20-minute sweat session can be enough to perk up your mood for a whopping 12 hours, reports a University of Vermont study. It may also be as effective as medication for treating depression in some people. And exercise can lead to changes in the brain that strengthen your resolve against stress.

Dr. Keri Peterson.
Women's Health, June 2010