What are the differences in calorie burning between muscle and fat? Live Science spoke to experts to find out. (Image credit: Juanmonino via Getty Images)
While some organs, such as the brain, function without interruption, other body tissues, such as muscle and fat, may be dormant. Muscles are generally inactive unless exercise occurs, while a special type of fat, brown fat, is activated exclusively in cold weather to help the body retain heat.
At rest, these two tissues burn very few calories, thus having little effect on weight loss. However, it is believed that when building muscle mass through exercise, larger muscles will burn more calories throughout the day. This implies that someone with a higher muscle to fat ratio will burn significantly more calories at rest than someone with a lower ratio.
But does that extra muscle mass really matter? What role does fat play in this process?
How Muscles Burn Calories
Calories are units of energy from food that fuel all body processes, with excess stored as fat. The bulk of calories are broken down by actively working organs such as the brain, heart, kidneys, and liver, each of which uses up 20 times more calories than relaxed skeletal muscle.
At the same time, inactive muscle and brown fat use very little energy: one pound (0.45 kg) of relaxed muscle burns 6 calories per day, while the same amount of fat burns only 2 calories per day. However, because muscle is one of the most abundant tissues in the body, it can burn a significant amount of calories when it is being used.
One study found that men doing strength training using hydraulic systems burned more than 12.6 calories per minute, while men running on a treadmill burned nearly 9.5 calories per minute—and it adds up fast. By comparison, one pound of muscle at rest burns just 0.004 calories per minute.
(Research shows that when body mass is taken into account, there are no significant differences in calorie expenditure during exercise between the sexes.)
“The best way to burn calories in any [exercise] session is definitely cardio,” says Edward Merritt, a kinesiologist at the University of Texas Southwestern. But most people can’t commit to intense cardio multiple times a week, so he says strength training, which builds muscle through exercise, is a more sustainable option.
However, Merritt cautions against the misconception that increasing muscle mass will increase your metabolism and tissue calorie burning even at rest. According to this myth, larger muscles supposedly burn more calories to maintain themselves, and each additional pound of muscle mass burns 50 calories per day at rest.
“If you’re just lifting weights and then sitting on the couch, those muscles aren’t necessarily burning significantly more calories,” said Gregory Steinberg, a metabolism researcher at McMaster University in Canada. However, “if you have more muscle mass, you’re going to be moving more weight, and therefore you’re going to burn more calories because you’re doing more work.”
Increasing muscle mass through strength training can help people burn more calories during exercise, Merritt told Live Science. That's partly because larger muscles tend to have more fast-twitch fibers, which require more calories to work, as opposed to slow-twitch fibers, which are designed for endurance.
Sourse: www.livescience.com
