Sweat it out on the treadmill or start pumping iron? A new study suggests that jogging (or similar aerobic exercise) is more effective than lifting weights for shedding fat lodged deep within the abdomen.
Unlike subcutaneous fat — the stuff that hangs over belt buckles and swings from the backs of your arms — abdominal fat, also known as visceral fat, is packed within the body around the internal organs. Studies suggest that visceral fat is most damaging to your health — it has been associated with increased risk for heart disease, diabetes and certain kinds of cancer.
So the new study by researchers at Duke University Medical Center sought to determine the best way to lose it. The researchers recruited 196 overweight and sedentary adults, aged 18 to 70, and randomly divided them into three groups: an aerobic-exercise group, who did the equivalent of jogging 12 miles per week at 80% heart rate; a resistance-training group, who performed three sets of 8 to 12 reps three times per week; and a combination group, who did both aerobics and strength training. All groups were closely monitored to make sure participants were putting in maximum effort.
At the end of the eight-month trial, the aerobics group had shed significant amounts of visceral fat and liver fat. They had also reduced their insulin resistance, liver enzymes and triglyceride levels — all risk factors for heart disease, stroke and Type 2 diabetes.
The strength-training group saw none of these benefits. Combining aerobic exercise and resistance training yielded similar results to aerobic exercise alone. Further, the researchers found that aerobic exercise burned 67% more calories than resistance training.
But if visceral fat hides deep within the body, how do you know you’ve got it? Reported NPR’s Shots Blog:
There’s no easy way to know how much visceral fat a person has; the researchers had to put people in CT scans to measure it. But one good clue is a beer belly. And men tend to carry more visceral fat than women, [lead author and exercise physiologist Cris] Slentz says, while white people tend to have more visceral fat than African Americans. And older people tend to internalize fat, while younger people carry fat right beneath their dewy skin.
If visceral fat is your greatest problem, the findings suggest you’re better off taking up jogging, biking, swimming, walking, using the elliptical machine or something similar, rather than lifting weights. (Still, resistance training is still a key part of physical fitness, increasing lean body mass and strength and improving metabolism.)
The good news is that you don’t have to exercise as intensely as the people did in the study. “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,” said Slentz in a statement.
The study was published in the American Journal of Physiology.
Meredith Melnick is a reporter at TIME. Find her on Twitter @MeredithCM. You can also continue the discussion on TIME’s Facebook page and on Twitter @TIME.