Muscle vs Fat: Calorie-Burning Comparison
How many more calories does muscle burn than fat? Live Science spoke with experts to find out.
While some organs, like the brain, work continuously, other body tissues, like muscle and fat, can enter an inactive state. Muscles are typically inactive except during exercise, and a special type of fat — called brown fat — activates only in the cold to help warm us up. When on standby, these two tissues burn very few calories and thus have a negligible impact on weight loss. But there’s a notion that, if you build your muscles through exercise, those bigger muscles will burn more calories throughout the day. It follows that a person with a higher muscle-to-fat ratio would burn many more calories while at rest than someone with a lower ratio. But does that extra bit of muscle really make a difference? And how does fat factor in?
Calories are units of energy from food that power every bodily process, and the body stores an excess of them as fat. Most calories are broken down by continuously active organs, like the brain, heart, kidneys and liver, each of which burns 20 times as many calories as relaxed skeletal muscle. Meanwhile, inactive muscle and brown fat use little energy: One pound (0.45 kilogram) of relaxed muscle burns 6 calories and the same amount of fat burns 2 calories in a day. But because muscle is one of the most abundant tissues in the body, it can burn a substantial number of calories when put to work.
Resistance Training Burns More Calories
One study found that men who performed resistance training with hydraulic systems burned more than 12.6 calories per minute, and men who ran on a treadmill burned nearly 9.5 calories per minute — and that adds up quickly. By comparison, one pound of resting muscle burns only 0.004 calories per minute. “The best way to burn calories in any given [workout] session would absolutely be cardio,” said Edward Merritt, a kinesiologist at Southwestern University in Texas. However, most people can’t find the energy to do intense cardio several times a week, so he argued that resistance training — which grows muscles by placing them under tension — is a more sustainable approach.
Muscle Growth Doesn’t Equal More Calories
Merritt cautioned against the misconception that muscles getting larger increases the tissue’s calorie-burning metabolism, even at rest. According to myth, larger muscles burn more calories to maintain themselves, and each pound of muscle gained burns 50 calories per day while at rest. “If you just lift weights and then sit on the couch, those muscles aren’t necessarily burning that many more calories,” said Gregory Steinberg, a metabolism researcher at McMaster University in Canada. However, “if you have more muscle, you will also be moving more weight around, and you’ll burn more calories because you’re doing more work.”
Brown Fat and Calorie Burning
Most of our fat is “white fat,” which is not helpful for burning calories; it mostly stores calories, insulates organs and releases hormones that regulate hunger. But humans also have “brown fat,” which burns calories to regulate body temperature in the cold. Brown fat burns only 2 calories per day when inactive, and it would burn 20 additional calories during 90 minutes of cold exposure. The same number of calories can be burned with two minutes of muscle-activating exercise. Ice baths may burn extra calories by inducing shivering, rather than activating brown fat, Steinberg suggested.
In conclusion, while building muscle through resistance training can help people burn more calories when they exercise, it’s essential to understand that muscle growth alone doesn’t significantly increase calorie burning at rest. Brown fat may play a role in calorie burning, but more research is needed to fully understand its impact on metabolism. Remember, it’s essential to find a balanced approach to exercise that works for you and promotes overall health and well-being.
Kamal Nahas, a freelance contributor based in Oxford, U.K., shared his expertise on this topic, shedding light on the latest research findings and insights. His passion for science and health drives his work, and his diverse background in pathology and immunology adds depth to his analysis. As a microscopist at the Diamond Light Source, he continues to explore the wonders of the natural world. When not immersed in research, you can find him exploring the Jurassic Coast, searching for fossils and connecting with the earth’s history.