Building Muscle to Lose Fat? Here's Why That May Not Be the Best Idea

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POPSUGAR Photography | Benjamin Stone
POPSUGAR Photography | Benjamin Stone

For the longest time, most people thought cardio was the most effective way to lose weight. Fortunately, this outdated fitness advice has been replaced; more people are eschewing the elliptical and treadmill for the weight room (and for good reason).

But while lifting weights can certainly help you lose weight, it shouldn't be your only method to burn fat. Damien M. Callahan, PhD, assistant professor in the department of human physiology at the University of Oregon, explained why.

"Muscles burn more calories at rest than fat does," Dr. Callahan told POPSUGAR. So having more muscle mass means you are burning more calories at rest than if you had that same amount of tissue as fat tissue. This will boost your metabolism, but not as much as you may think — muscle burns 13 calories per day per kilogram of muscle tissue, compared to fat just burning 4.5 calories per day per kilogram of fat tissue.

But in terms of a weight-loss strategy, just focusing on building muscle isn't the best approach, he said. "If you really want to change your resting metabolism in a way that will affect your body weight, [building muscle] is an inefficient way to go about it."

That doesn't mean you shouldn't try to build muscle; having more muscle mass means you can power through your workouts better and burn more calories during exercise. But the amount of muscle you would need to put on to overhaul your metabolism is "pretty substantial," Dr. Callahan said.

"It's really, really hard to add many kilograms of muscle that would give you 100, 200, 300 calories extra burned per day just sitting around," he explained. "That said, if you're doing a lot of training and you have more muscle mass, then it's gonna help. But as a primary strategy for weight loss, it's probably not the best way to go."

Instead, a better weight-loss strategy is to adjust your calorie intake combined with exercise, ideally a mix of resistance and endurance training — the ratio of each will depend on each person and their fitness goals. Overall, he recommends simply making lifestyle changes that you'll stick with.

"I think the biggest thing that can be done is to adopt a change that's more sustainable," he said. "Ultimately, it's just a lot harder to exercise enough to burn 500 calories than it is to just not eat a 500-calorie dessert. So the strategies for weight loss generally are more successful that include some kind of diet and also exercise. It's very, very hard to exercise alone to an extent that's sufficient to burn those calories."