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“Resistance training is a very good way to increase lean muscle, and aerobic exercise isn’t. But if the goal is to lose fat, then aerobic exercise is the ticket.” Cris A. Slentz, PhD (NPR, August 26, 2011) [Maybe not]
Aerobic Exercise Beats Weights for Reducing Belly Fat
Another Way: Turbocharge Your Metabolism
Duke University researchers led by Cris A. Slentz, PhD, compared aerobic training (AT) and resistance training (RT) alone and in combination (AT/RT) as effective means of reducing fat in various locations and improving insulin resistance. AT was the clear winner.
They divided 196 overweight, sedentary adults (18 to 70, men and women) into three training groups. One group trained with Cybex weight lifting machines three times a week (8 exercises, 3 sets, 8-12 reps). A second group did the equivalent of jogging 12 miles a week at 75% VO2max, including treadmill, stationary bike, elliptical trainer or any combination. A third group did AT and RT, in that order. Following a four-month break-in period, all three groups trained for eight months. (144 completed the study.)
All subjects were asked to maintain their current lifestyle during the break-in period and the three training periods.
The AT group lost a significant amount of visceral fat—the deep belly fat around internal organs—subcutaneous fat (fat under the skin) and total fat; insulin resistance also improved. RT resulted in decreased subcutaneous fat, but did not significantly improve the other variables. The results for AT and RT combined were essentially the same as aerobic training alone. Adding resistance to aerobic training—and spending roughly twice as much time—produced no significant additional improvement in the variables studied.
(Visceral fat is associated with diabetes, heart disease, and other metabolic problems: http://www.cbass.com/Deepfatdeadly.htm )
Importantly, aerobic training burned 67% more calories than resistance training. (See below)
“A moderate amount of aerobic exercise is the most time efficient and effective” way for overweight people to lose fat and improve insulin resistance, Dr. Slentz and his group concluded. They acknowledge that aerobic training is not a good way to increase or maintain lean muscle.
The results were published in the American Journal of Physiology.
Does that mean weight training is a waste of time?
We’ll look at the Discussion portion of the study, and then add some thoughts of our own.
Calories Key Factor
The researchers emphasized that resistance training is known to result in significantly lower calorie expenditure than vigorous aerobic training. RT training creates less oxygen demand, roughly 45% of maximum compare to 75% for the AT in their study. They estimated that the AT program expended 67% more calories than the RT program. “We would hypothesize that much of the difference in the effects on ectopic (abnormal) fat are due to the difference in calorie expenditure between the two training programs,” they wrote.
Interestingly, Slentz et al related that a two-year study reported that visceral fat increased seven percent with RT, which was significantly better that the 21% increase observed in their inactive controls. “This is an important finding and indicates the need for more research in this area,” they wrote. It appears that resistance training can have a positive effect on visceral fat levels. Visceral fat containment is apparently not the exclusive province of aerobic exercise.
In another result from the same groups studied here, Slentz et al reported that the AT/RT group experienced the most robust and widespread benefits, and significantly improved metabolic syndrome score, waist circumference, triglycerides, and diastolic blood pressure. “Whether this robust response was due to a synergistic effect of AT plus RT, or simply due to the greater total amount of exercise cannot be determined from this study design,” they wrote. Again, total calorie burn may be the overarching factor.
Slentz et al closed their discussion with a telling suggestion: “Future research directions for comparing RT and AT could include two programs matched for calorie expenditure.” They suggest comparing a lower intensity aerobic training plan and a RT plan similar to the one in this study. “Previous research has shown that AT effects on ectopic fat follows a dose response relationship,” they observe. Results improve with the increase in calorie expenditure. “This would allow a more direct comparison of the RT benefits that are specific to muscle mass increases and the AT benefits which are specific to oxidative/mitochondrial changes,” they observe.
As things now stand, calorie burn appears to be the key factor in reducing or controlling fat around internal organs and elsewhere. We believe there’s a better way to expend calories than that suggested by the Slentz group.
A Better Way
“The midsection of a 67-year-old is not a pretty sight,” a famous money manager, a runner, wrote recently in a newsletter. “No matter how many sit-ups I do…there are no six-pacs (his spelling) there, or anywhere in the vicinity for that matter,” he added. He conceded, however, that “many six-packs” over the years has contributed to the problem.
Whatever he’s doing isn’t working. I believe he needs to work on calorie balance. My impression is that running has been his main exercise for many years. As shown in the Slentz study, jogging burns lots of calories—more than lifting. But it doesn’t work muscle fibers all over the body like resistance training. Muscle fibers that aren’t used shrivel up and die. That can be a huge problem, because muscle mass drives metabolism. Joggers end up operating on an hybrid metabolism, when they could be motoring alone on a calorie-guzzling eight cylinder. That makes it more difficult for joggers to create an energy deficit and get rid of the fat all over their body.
This becomes especially troublesome as the years pile up. My friend Dr. Richard Winett, an expert on healthy aging, wrote in an email, “Long endurance work is a mistake because it basically is ‘catabolic’ and by middle age and certainly older people are losing muscle mass.”
We’ll come back to the calorie-burn side of the energy equation in a moment; we need to talk about the calories-in side first.
My money manager friend (we once corresponded) was right about the contribution of beer to his “one-pac.” Excess calories (from any source) compound the problem. The solution is to eat foods that fill you up without giving you too many calories. That means eating lots of whole grains, fruits, and vegetables, combined with lean protein and good fat. Have a small glass of wine in the evening—and maybe an occasional beer. But no six-packs!
Back to the energy expenditure side: I have a suggestion that will burn as many or more calories than jogging, while keeping your metabolism roaring along 24-hours a day. My plan has three parts: resistance training (whole body), high-intensity intervals (less time, more effective), and low-intensity physical activity between workouts to burn extra calories and facilitate recovery. Walking would be an example of the third element. (You’ll find many articles on high-intensity intervals in our “Aerobic Exercise” category.)
Combined with a healthy balanced diet, that three-pronged exercise combination provides an effective and time efficient way to balance calorie intake and expenditure.
* * *
This plan, of course, describes my diet and training philosophy, which you’ll find summarized on this website: http://www.cbass.com/PHILOSOP.HTM
If you’re wondering if it works, this photo by Pat Berrett shows me at 60
We’re planning more photos next year, on the eve of my 75th birthday.
“You have clearly demonstrated in an N=1 study that there is a much better approach to what the Slentz group is trying to do,” Professor Winett wrote in the same email message.
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