Exercisers seeking weight loss have long debated what the best way to lose fat might be. While some argue that cardio is the fastest way to a whittled waistline, others suggest that the metabolism boost offered by weight and resistance training is a better route to take in the battle of the bulge.
Now, researchers at Duke University are closer to an answer: in a study of 119 overweight or obese adults, aerobic exercise beat out resistance training and a combination of aerobic and resistance training in terms of losing fat mass.
“Given that approximately two-thirds of adults in the United States are overweight due to excess body fat, we want to offer clear, evidence-based exercise recommendations that will truly help people lose weight and body fat,” said Leslie H. Willis, MS, an exercise physiologist at Duke Medicine and the study’s lead author in a statement.
Researchers gave three different exercise protocols to participants: either aerobic activity only, equivalent to about 12 miles or 133 minutes per week; resistance training only, meaning three days per week of lifting weights for a total 180 minutes per week; or a combination of aerobic activity and weight lifting for a total 313 minutes per week. Before and after the exercise regimen, they tested the body compositions of each person.
They found that aerobic activity alone was the most effective and efficient for losing fat mass and overall body mass. Those who did cardio-only lost the most weight and the most fat specifically. Those who did both cardio and weight lifting also lost fat mass and overall weight, though less so than cardio-only. They did decrease their waist circumferences, on average, more than the cardio-only group, though researchers chalked this up to the overall duration of their exercise -- nearly double that of the cardio-only group.
By contrast, the resistance training group did not lose a significant amount of fat or overall weight. In fact they gained lean body mass, leading to overall weight gain. Those who advocate resistance training suggest that the lean mass increases resting metabolic rate, which could lead to overall fat loss. However, that didn't bear out in the study.
“No one type of exercise will be best for every health benefit,” Willis said in the statement. “However, it might be time to reconsider the conventional wisdom that resistance training alone can induce changes in body mass or fat mass due to an increase in metabolism, as our study found no change.”
The study was published in the Journal of Applied Physiology on Dec. 15.