Weights or Aerobics for Fat Burning? It’s All About Energy Expenditure

by Paul Rogers on September 5, 2011

I’m always amazed at how easily nonsense gets a hold in the fitness community and spreads like wildfire. One concept that has received widespread dissemination over a decade or longer is that weight training is better for fat loss than aerobic training. Various ideas about this have been propagated, including more muscle means more resting energy expenditure, and post-exercise energy expenditure is greater with resistance training versus running or aerobics.

The trouble with this propaganda — and I have no bias,  having equal fondness of weights and aerobics — is that it never did hold up, and I said so. As long as one made some attempt to compare workout sessions of somewhat equal duration and conclusion, running was always going to have considerably superior energy expenditure, perhaps at least 50% more. An hour run at >80% of max heart rate is going to burn in the region of 700-1000 kcalories (3000-4200 kjoules) depending on body mass and resting metabolic rate. A similar weights session, in my estimation would be hard pressed to exceed 600 kcalories (2500 kjoules). Okay, you can ramp it up with high-intensity, whole-body exercises like hang cleans and thrusters and power cleans and heavy sets of Romanian deadlifts with little rest between sets, and that’s what you have to do to increase energy expenditure, but for the average weight trainer, the ‘jog’ is always going to work better for energy expenditure and fat loss.

And here’s the new evidence. In this study of 196 overweight, sedentary adults by the Duke Medical Center, jogging 12 miles (20 km) a week, used about 67% more energy than doing weights three times a week with 3 sets of 8 to 12 repetitions for 8 exercises. The extra fat burned off with running was the more dangerous visceral fat around the internal organs like the liver.

I made an almost identical point in my article here on How to Burn More Fat. Movement is always going to increase the metabolic cost. What about the weight training afterburn I hear the hoards screaming! If you jog at 80% of maximum heart rate you are getting beyond the moderate and into the higher intensity training zone. Excess post-exercise oxygen consumption (EPOC or afterburn) is going to be increased and match any weight training EPOC, but it won’t make too much difference because energy expended during the exercise itself is where the main game is.

To get weights and resistance training up there matching aerobics for energy expenditure and fat burning, you need to move — and that, more or less, means circuit training where you move quickly between weights exercises and keep the heart rate up with some step or treadmill work as well.

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