Aerobic exercise bests resistance training at burning belly fat

This isn't the fat that lies just under your skin and causes the dreaded muffin top. Belly or abdominal fat -- known in scientific communities as visceral fat and liver fat -- is located deep within the abdominal cavity and fills the spaces between internal organs. It's been associated with increased risk for heart disease, diabetes, and certain kinds of cancer.

"When it comes to increased health risks, where fat is deposited in the body is more important than how much fat you have," says Duke exercise physiologist Cris Slentz, Ph.D., lead author of the study published in the American Journal of Physiology. "Our study sought to identify the most effective form of exercise to get rid of that unhealthy fat."

The Duke study showed aerobic training significantly reduced visceral fat and liver fat, the culprit in nonalcoholic fatty liver disease. Aerobic exercise also did a better job than resistance training at improving fasting insulin resistance, and reducing liver enzymes and fasting triglyceride levels. All are known risk factors for diabetes and heart disease.

Resistance training achieved no significant reductions in visceral fat, liver fat, liver enzyme levels or improvements in insulin resistance. The combination of aerobic with resistance training achieved results similar to aerobic training alone.

"Resistance training is great for improving strength and increasing lean body mass," says Slentz. "But if you are overweight, which two thirds of the population is, and you want to lose belly fat, aerobic exercise is the better choice because it burns more calories." Aerobic training burned 67% more calories in the study when compared to resistance training.

The eight-month study followed 196 overweight, sedentary adults (ages 18-70) who were randomized to one of three groups: aerobic training; resistance training or a combination of the two. The aerobic group performed exercises equivalent to 12 miles of jogging per week at 80% maximum heart rate. The resistance group performed three sets of 8 -- 12 repetitions three times per week. All programs were closely supervised and monitored to ensure maximum effort in participation.

While the training programs were rigorous and substantial, Slentz says their previous research leads him to believe similar results could be achieved with a more moderate aerobic exercise program.

"What really counts is how much exercise you do, how many miles you walk and how many calories you burn," he says. "If you choose to work at a lower aerobic intensity, it will simply take longer to burn the same amount of unhealthy fat."

Additional Duke co-authors include: Lori A. Bateman, M.S., William E. Kraus, M.D., Leslie H. Willis, M.S., A. M.S., Lucy W. Piner, M.S., Victoria H. Hawk, M.P.H., R.D., Michael J. Muehlbauer, Ph.D., Greg P. Samsa, Ph.D., Rendon C. Nelson, M.D., Kim M. Huffman, M.D., Ph.D., Connie W. Bales, Ph.D., R.D.

The following co-authors are affiliated with East Carolina University, which was also a training site for this study: A Tamlyn Shields, M.A.. Charles J Tanner; Joseph A. Houmard, Ph.D.