Question: How many calories can be burned by a pound of muscle?

Answer: One pound of muscle burns about five calories in a 24 hour period when the muscle is at rest.

This fact is contrary to what is commonly stated. You may have heard that anywhere from 10 to 50 calories can be burned by a pound of fat in a 24 hour period.

Why is there confusion?

The Katch-McCardle Formula used to calculate metabolic rates shows that a persons daily metabolic rate can be calculated as: 370 + (21.6 X LBM(kg)) = Calories burned in a 24 hour period.

Many people think that, if a kilogram of muscle burns 21.6 calories in 2 hours, a pound of muscle must burn about 10 calories.

This is not true.

A pound of lean body mass is not the same thing as a pound of muscle. Lean body mass includes everything in your body that isn’t fat, which means that the calculation includes highly metabolic tissues like your liver, heart and viscera.

When you add lean body mass to your body through resistance training, you are adding muscle mass. You aren’t adding mass to your organs. And even though you have more muscle in your body than organs, they only share about half of the metabolic work.

For every pound of muscle you gain from working out, you can expect to burn an extra five calories in 24 hours while your body is at rest.

Adding muscle to boost your metabolism may not work like you would like it to. If you want to burn fat, rely on your diet.

There is some confusion about what makes a person gain and lose muscle.

When a person is bedridden, he or she loses muscle. A person on a low-calorie diet will also lose muscle.

When I was researching the Eat Stop Eat program, I obtained input from several dietitians, and all of them spoke of bedridden or low-calorie-diet patients who had lost muscle mass.

A reduction in calories doesn’t necessarily cause you to lose muscle if you continue to exercise. Being bedridden, then, should be the only reason a person loses muscle mass.

Have you ever had to wear a cast due to an injury? When your cast came off, your injured limb was skinnier than it had been.

The limb that was in the cast received the same nutrients as your other limbs. The only difference is that that limb wasn’t being used.

Putting a cast on a limb causes muscle loss so effectively that researchers use it to study “disuse atrophy” – or muscle loss from lack of use.

Researchers at the University of Nottingham placed casts on the right legs of 22 individuals for a two-week period. The individuals maintained their normal diets, but when the casts were removed, the cross-sectional area of their thighs had decreased by 10 percent. All muscle fiber types experienced a decrease in muscle diameter.

Muscles are “contractile units” – not “storage units” like fat cells. Your fat cells store or release energy in response to what you eat. Muscles respond to work.

If your muscles aren’t challenged, their size will not increase. If they aren’t challenged for a prolonged period of time, their size will decrease.

Muscle mass will not be lost as long as you continue to exercise and meet a caloric minimum – studies found out as low as 80 grams of protein and 800 Kcals per day over the course of several weeks.

Multiple meals and extra protein isn’t necessary for you to keep from losing muscle. The key to maintaining your muscle mass is exercise.

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Reference:
Hespel P. Journal of Physiology (2001), 536.2, pp.625–633
APPELL, H. J. (1990). Sports Medicine 10, 42–58.