Belly fat, also known as abdominal fat, intra-abdominal fat or visceral fat is located inside the abdominal cavity, packed in between the stomach, liver, intestines and other organs. Belly fat is different from fat under the skin (subcutaneous fat) and intramuscular fat which is interspersed in skeletal muscles. People with excessive amounts of visceral fat have a higher risk of developing diabetes, heart disease, and some cancers.
Aerobic exercise is any physical activity which raises the heartbeat and makes the lungs and heart work harder to meet the body's increased demand for oxygen. Aerobic exercise raises the circulation of oxygen through the blood. Examples include jogging, running, swimming, cycling, rowing, and skipping.
Resistance training is any physical activity that uses the force of a muscle against some kind of resistance to build muscle strength and size. Examples include weight training, push-ups, chin ups, and moving or holding in position elastic/hydraulic devices.
Lead author, Cris Slentz, PhD, an exercise physiologist, said:
"When it comes to increased health risks, where fat is deposited in the body is more important than how much fat you have. Our study sought to identify the most effective form of exercise to get rid of that unhealthy fat."
"Resistance training is great for improving strength and increasing lean body mass. 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."
The investigators found that aerobic exercise consumed 67% more calories than resistance training.
They tracked 196 adults aged between 18 and 70 years. They were all overweight and had led sedentary lifestyles. The volunteers were randomly selected into three groups:
- Aerobic training group - they did the equivalent of 12 miles jogging weekly, at 80% maximum heart rate
- Resistance training group - they did 3 sets of 8-12 repetitions three times per week
- Combination group (aerobic plus resistance
They found that aerobic training reduces visceral fat and liver fat considerably. Aerobic training was also found to be better at improving fasting insulin resistance, compared to doing weights. It also reduced liver enzymes and fasting triglyceride levels more effectively. All these are risk factors for heart disease and diabetes.
The authors wrote that resistance training had virtually no impact on levels of visceral fat, liver enzyme levels, liver fat, or insulin resistance. Combining resistance training with aerobic exercise was found to have similar results to just doing aerobic exercises.
Even though the training program in this study was "rigorous and substantial", Slentz believes that people could achieve similar results with milder aerobic exercise regimes.
"What really counts is how much exercise you do, how many miles you walk, and how many calories you burn. If you choose to work at a lower aerobic intensity, it will simply take longer to burn the same amount of unhealthy fat."