Why lifting weights is better than cardio if you're trying to lose fat

Weightlifting is totally better for fat loss than cardio, because broscience.

In this case I’m going to agree with the bros; even though I’m a Boston Marathon qualifier, there is a compelling argument why lifting weights is the best way to burn fat.

Hang on; it’s complicated.

Muscle Mass and Metabolism

One book I recommend is Strength Training for Fat Loss by Nick Tuminello. It provides detailed instruction on lifting weights in a manner that is metabolically costly. That means you burn a lot of calories doing it, plus you build muscle. Awesome.

It’s the “build muscle” part where the author perpetuates a myth, however. In an otherwise great book, Nick says that a pound of muscle burns an extra 30 calories per day while at rest. His source for this is another excellent book: The M.A.X. Muscle Plan by Brad Schoenfeld. (I interviewed Nick and Brad for this piece on weight machines; they’re two of the wisest men in weightlifting.)

Brad doesn’t offer an original source for the metabolic rate of muscle at rest. Indeed, I’ve never seen any scientific backing for the claim. It’s apocryphal, and I busted it a while back for the Los Angeles Times, interviewing a metabolism researcher and looking at multiple scholarly sources. The reality is that muscle only burns about 6 calories per pound per day while at rest, and if you’re dropping a lot of fat, you also need to account that a pound of fat burns about 2 calories per pound/day at rest.

Hypothetically, if you gain 20 pounds of muscle and lose 60 pounds of fat, you break even in terms of effect on resting metabolism. This doesn’t even take into account that you’re 40 pounds lighter overall for every step you take and every flight of stairs you climb, meaning fewer calories burned each day.

The Caloric Cost of Cardio vs. Lifting

Even though Tuminello’s program is high intensity, it’s still not going to equal a hard cardio workout. Essentials of Strength Training and Conditioning puts “vigorous” weightlifting at 6 METs (six times resting metabolism). Compare this to a fast-ish run of 7.5 mph, and the caloric burn rate is more than double at 12.5 METs. As an example, a guy who weighs 220 will burn about 100 calories per hour on the couch, 600 calories per hour at vigorous lifting, and 1,250 calories per hour running at 7.5mph.

Nick’s program is probably even higher than 6 METs, because he uses a circuit that makes it “extra vigorous,” but as someone who is both a lifter and a runner, I can’t see this intensity matching the caloric burn rate of a hard run. Oh, and never mind about caloric “after burn” for cardio or weights. It’s been way overblown.

It's worth mentioning the broscience articles that say cardio slows your overall metabolism. Duh. Any exercise will do that. That’s what getting in shape means. Fine-tuning your body into a higher performance machine, via either weights or cardio, doesn’t turn it into a “fat incinerating blast furnace” while at rest. It makes it more efficient, and added muscle mass doesn’t make much of a dent in this.

There is more to this story, however.

Comparing Via Clinical Study

2012 study of 119 overweight or obese people published in the Journal of Applied Physiology randomized them into three groups: Resistance training alone (RT), aerobic training alone (AT), or both.

Nutrient Partitioning

This bears mentioning, because when you add muscle it requires a partitioning of some of your calories. It takes about 2,500 calories to build a pound of muscle, whereas you need to burn 3,500 calories to lose a pound of fat. What this means is that for every pound of muscle you build, that’s 2,500 calories worth of foods that build muscle that you didn’t have to worry about in terms of your overall energy balance equation for losing fat.

But still, look at those two graphs. Even gaining muscle didn’t seem to make much difference for these folks in the just RT group. What’s more, eventually you’re going to stop building muscle, so this benefit is finite.

And yet, it is important to realize that …

Life Is Not a Clinical Study

It’s one study of sedentary and overweight/obese people, and not necessarily representative of what happens in the real world. That study is a pretty literal translation of the caloric cost of AT vs. RT. But the way people behave in the real world can be different, especially over time. This study lasted for eight months, but when it comes to physique transformation at the individual level, it can be a years-long project that involves different behavioral parameters than an interaction between scientists and study volunteers.

And what all of this has ignored so far is that …

Lean Bodies Are Made In The Kitchen

No matter the exercise type, burning calories is the least important thing exercise does. I’ve been saying this for years. Performance enhancement and health improvements are more important, but when it comes to fat loss, the ability to change eating behavior is a significant benefit of regular exercise.

Exercise increasing appetite is a bogus myth that is based either on extreme amounts, like marathon training, or because of a psychological effect of “I exercised, therefore I earned this treat.” I’ve examined how exercise affects appetite for my Chicago Tribune column, and what it boils down to is that intense exercise builds up the brain power for making better eating decisions. There is some evidence that aerobic exercise may do this better than weightlifting, but that’s a clinical study and this is the real world. I know that it takes plenty of brainpower to push hard with weights. These pumped up cognitive capabilities can be used to transform you into a better eater by enhancing your ability to plan, make decisions, and control the impulse to eat high calorie treats.

So, maybe the brain boost with aerobic exercise is better for dietary control than weightlifting is, but I’m still sticking to my original claim that hitting the iron can be better for fat loss.

I’m finally going to tell you why.

Psychology Rules

It hit me one day while cycling; an epiphany that flushes much of this information down the toilet. Humans are unique creatures with unique motivations. I know so many who love lifting and never do anything aerobic, and they’re lean. Conversely, I know plenty of aerobic junkies who have higher body fat percentages. I’ve met hundreds, possibly thousands of lifters who don’t do anything aerobic, and vice versa. And the lifters are usually leaner.

What gives? Here’s the aforementioned epiphany.

I don’t have a scientific study, but rather two decades of observation and talking to people, plus logic and some good guesses. Weightlifting seems to create a mentality where aficionados are more concerned about what and how much they eat. Visit any weightlifting blog / message board and nutrition and fat loss are hot topics. Conversely, those who only do aerobic activity seem to pay less attention to nutrition, or even use it as an excuse to eat. I’ve sure done it. Many a long bike ride has been done to earn a night of drunken gluttony.

People who lift often do so in a social environment. There is usually (but not always) more emphasis placed on vanity. They talk to one another. They get nutritional advice from trainers (not always the best idea, but that’s for another article), and sometimes, when working with a trainer, clients feel more obligated to get results, and this includes paying more attention to the nutritional aspect.

Runners, swimmers and cyclists are often engaged in a solo activity and not with regular coaching. It has been my experience with this community that they care less about what gets shoved into the pie hole.

The plural of “anecdote” is not “data,” but in the absence of data there is an observation: runners mostly talk about running (and running playlists), and lifters more often talk about nutrition.

So there you go.

Check out this graph (Figure A). RT is on the left, AT in the middle, and both on the right:


Obviously, both is the way to go for fat loss, but it’s also worth noting that, for this study, doing both took twice as long as just RT or AT. Not everyone has that kind of time or motivation.

But what about changes in muscle mass? We have another graph (Figure B):


Whoa, that really sucks for aerobic training. They lost muscle. And it still “killz gainz bro” a little when coupled with RT. Using this study as an example, strict RT gained the most lean body mass.

So far, for fat loss, aerobic training is winning. But we’re not done.

But What to Do?

Now that you know all this, what choice should you make? Personally, I’m a fan of both RT and AT because they compliment each other, and in a perfect world you would give them fairly equal time. However, if you really are time / motivation pressed and can only choose one (and personal preference doesn’t factor in), the logical choice is the iron (Nick and Brad’s books are good resources). The reason why is that weightlifting does amazing things for your physique and health that nothing else can, whereas there are other ways to integrate plenty of calorie-burning aerobic activity into your daily routine that don’t involve running shoes, bikes, pools, Zumba classes or elliptical trainers.

But if you do choose to go solely aerobic, take heed about care with nutrition, and feel good that you’re lapping everyone on the couch.

James S. Fell is a syndicated fitness columnist for the Chicago Tribune and author of Lose It Right: A Brutally Honest 3-Stage Program to Help You Get Fit and Lose Weight Without Losing Your Mind, published by Random House Canada. Visit his site at www.BodyForWife.com for a free weight loss report. Follow him on Facebook and Twitter.

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