Experts say if you have to choose between a diet or exercise to lose weight, choose exercise. A new study suggests it's better to hit the weight room than cut back on how much you eat.

    And although the goal is the same -- use more energy than you stockpile -- working out has more benefits.

    People who exercise tend to be stronger, have more muscle mass, and an increased aerobic capacity. Dieters tend to lose muscle mass and strength.

    "If push comes to shove and somebody wants to know if they should diet or exercise to lose weight, I would suggest exercise, provided they are willing to put in the extra time and effort and not offset the gains they make by eating more," said study lead author Edward Weiss, a researcher at Saint Louis University's Doisy College of Health Sciences.

    Weiss and his colleagues studied 34 people between the ages of 50 and 60 who were in the high end of normal weight or overweight. Of the participants, 18 dieted while 16 exercised.

    The dieters reduced their calorie intake by 16 percent the first three months and 20 percent for the next nine months. The exercise group worked out to burn 16 percent more calories the first three months and 20 percent the following nine months.

    Both groups lost around 9 to 10 percent of their body weight. But the dieters lost muscle mass, while the exercisers did not.

    "It's important that dieting not be seen as a bad thing because it provides enormous benefits with respect to reducing the risk of disease and is effective for weight loss," Weiss said. "Furthermore, based on studies in rodents, there is a real possibility that calorie restriction provides benefits that cannot be achieved through exercise-induced weight loss."

    The study is detailed in an online edition of the Journal of Applied Physiology.