Is strength training really better than cardio for weight loss?
I did a radio interview today with Angela Kokott on QR77 in Calgary, and one of the questions we discussed was the perennial claim that lifting weights is better than aerobic exercise for burning calories. It’s a claim that isn’t totally crazy — even the most recent American College of Sports Medicine position stand on weight loss reverses earlier stands by acknowledging the possibility that resistance training could contribute to weight loss by elevating resting metabolic rate, increasing fat oxidation, and making people more active generally. Here’s the funky flowchart they use to illustrate this process:
Still, the “evidence statement” endorsed by the position stand is: “Resistance training will not promote clinically significant weight loss.” In other words, it’s a nice theory, but the studies of actual people losing weight don’t back it up.
The reason I bring this up is that James Fell has a good article in the Los Angeles Times that tackles this topic — in particular, taking on the oft-repeated whopper that every pound of muscle burns an extra 50 calories a day. He turns to Claude Bouchard of Pennington Biomedical Research Center, who offers the following breakdown of resting metabolic rate (RMR):
Brain function makes up close to 20% of RMR. Next is the heart, which is beating all the time and accounts for another 15-20%. The liver, which also functions at rest, contributes another 15-20%. Then you have the kidneys and lungs and other tissues, so what remains is muscle, contributing only 20-25% of total resting metabolism.
The punchline, according to Bouchard: a pound of muscle burns about six calories a day while a pound of fat burns two calories a day. Don’t get me wrong: strength training is great for many reasons, and I certainly encourage everyone (including, reluctantly, myself) to do some. But it’s not a miracle weight-loss technique.