In the quest for fitness and effective weight management, understanding how the body burns calories is crucial. Recent discussions have highlighted the role of muscle versus fat in calorie expenditure, with insights from experts shedding light on common misconceptions. While a pound of resting muscle burns more calories than an equivalent weight of fat, the difference may not be as significant as some believe. Furthermore, continuously active organs such as the brain, heart, kidneys, and liver play a pivotal role in the body's overall energy expenditure.
Muscle tissue, even at rest, consumes more energy than fat. Specifically, one pound (0.45 kilograms) of relaxed muscle burns approximately six calories per day. In contrast, a pound of fat expends only two calories daily. This disparity suggests that individuals with more muscle mass could potentially burn more calories even when not engaging in physical activity. However, experts stress that the difference is modest, as both muscle and fat use little energy when inactive.
Brown fat, a type of fat tissue known for its calorie-burning abilities, also burns around two calories per day when inactive. Interestingly, brown fat can burn an additional 20 calories during 90 minutes of cold exposure. This thermogenic capability has intrigued researchers, yet it remains unclear if people have enough brown fat to leverage it effectively for weight loss.
"People probably don't have enough brown fat to leverage it for weight loss," said Gregory Steinberg, a metabolism researcher at McMaster University in Canada.
The organs that work continuously—such as the brain, heart, kidneys, and liver—are major contributors to daily calorie expenditure. They burn 20 times as many calories as relaxed skeletal muscle. This insight emphasizes the substantial energy demand of vital bodily functions that operate irrespective of physical activity levels.
Despite the limited caloric burn of resting muscle and fat, growing muscles through resistance training can significantly boost calorie expenditure during exercise. Resistance training, particularly with hydraulic systems, can lead to substantial calorie burn. Research has shown that men engaging in such training burned over 12.6 calories per minute. Comparatively, running on a treadmill resulted in nearly 9.5 calories burned per minute.
"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," explained Gregory Steinberg.
For those seeking to maximize calorie burning during workouts, cardio remains a highly effective approach. Edward Merritt, a kinesiologist at Southwestern University in Texas, emphasized the benefits of cardiovascular exercises.
"The best way to burn calories in any given [workout] session would absolutely be cardio," stated Edward Merritt.
While vigorous exercise can increase brown fat levels, it is important to consider the limitations of relying solely on muscle mass for weight management. Gregory Steinberg cautioned against overestimating the calorie-burning potential of muscles at rest.
"If you just lift weights and then sit on the couch, those muscles aren't necessarily burning that many more calories," Gregory Steinberg noted.
Cold exposure also presents an intriguing avenue for activating brown fat's thermogenic properties. However, Merritt warned about the potential drawbacks of extreme cold during exercise.
"If it gets too cold, you limit your blood flow to areas that might need it and it limits your ability to perform the exercise," advised Edward Merritt.
