Fat Burning and Muscle Confusion

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The hallowed halls of the Academy of Broscience contain untold tomes of knowledge, wisdom, and recipes for “sick” pump stacks. Over the years, their scholars have elucidated the arcane esoterica of muscle confusion, thereby making it palatable for the layman. They discovered that any gram of carbohydrate eaten after dusk turns immediately to fat, and that curling in the squat rack engages more muscle fibers than curling elsewhere. Their field researchers are reportedly close to confirming the existence of spot reduction. But perhaps their greatest contribution to modern physical culture has been the establishment of the unassailable fact that muscle burns fifty times more calories than fat, at fifty calories per pound per day. (Even Dr. Oz says it, so it must be true.) As they have so painstakingly shown, adding twenty pounds of muscle increases your resting metabolic rate by 1000 calories. With that kind of leeway, you could eat a delicious twenty egg-white microwaved omelet with low-fat cheese and a side of plain oats and never worry about body fat accumulation!

This, of course, is complete nonsense. Broscience is not even peer-reviewed and their application for accreditation is still in administrative limbo.

No, but seriously: the idea that muscle significantly boosts resting metabolic rate is pretty much nonsense. Now, don’t get me wrong. I like muscle. Love it, even. Nothing I like more than a bit of lean mass, but I don’t like how this notion of “muscle burning fat at rest” has taken hold in the collective psyche. It leads to lofty expectations that come thundering down to shatter to pieces. It gets people on a single, obsessive fitness track where all they want to do is lift, lift, and lift (and eat, eat, eat) some more to the exclusion of other, perhaps more enjoyable pursuits. And, it can even negatively impact one’s health or progress toward desired body composition, either via overtraining the heavy lifting and undertraining the other stuff, like sprints, walks, hikes, and simple play.

Anyway, I came across an article several months ago detailing the author’s discovery that muscles don’t actually burn that many more calories than body fat. He doesn’t cite any specific studies, but he does cite Claude Bouchard, an obesity researcher from the Pennington Biomedical Research Center, who revealed that a pound of muscle, at rest, burns about six calories per day (and a pound of fat burns about two). That’s a far cry from the 50 calories per day figure “cited” by others. This number isn’t available in the abstract of some specific study. It’s drawn from extensive reading of the “biochemical and metabolic literature”. If you have literature to suggest otherwise I’m all ears. For the purposes of this post, though, I’ll take Claude at his word.

So, straight from the guy that studies this stuff for a living, muscle doesn’t burn a significant number of calories at rest. To illustrate the point let me quote the author of the LA Times article:

The 20 pounds of muscle I’ve gained through years of hard work equate to an added 120 calories to my RMR. Not insignificant, but substantially less than 1,000. However, I also engaged in a lot of aerobic activity and dietary restriction to lose 50 pounds of fat, which means I also lost 100 calories per day of RMR. So, post-physical transformation, my net caloric burn is only 20 calories higher per day, earning me one-third of an Oreo cookie. Bummer.

Or a single macadamia nut as the case may be. But that doesn’t mean having more muscle isn’t good for body composition and overall leanness, because it definitely is. Let’s look at some of the metabolic and other benefits of having more muscle mass.

Recent epidemiology (13,644 participating subjects) reveals that skeletal muscle mass strongly correlates with improved insulin sensitivity. With each 10% increase in skeletal muscle index (a measure of how much muscle is on one’s body), HOMA-IR (a measure of insulin resistance) saw a relative reduction of 11%. Folks with higher insulin sensitivity have better glucose control (carbs don’t destroy them) and lower rates of diabetes. Another study looked at the relationship between sarcopenia, or muscle wastage, and insulin resistance. There was a distinct relationship between sarcopenia and insulin resistance, independent of obesity, which can also exacerbate insulin resistance. So, based on epidemiology, a lack of muscle is linked to increased insulin resistance and poor glucose regulation. This should go without saying, but sarcopenia was also linked to obesity.

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