6 Things to Know About Non-exercise Activity Thermogenesis | Fitness Resources
Your metabolism is always working to burn energy. During periods of higher activity, your body will burn more calories than when you are at rest. (Note: A calorie is just a measure of unit of energy; technically speaking, it's the energy required to heat one liter of water by one degree centigrade.) But even at rest, your body is always expending energy. How you burn energy or expend calories, which is called the total daily energy expenditure (TDEE), can be organized into three distinct categories: Basal metabolic rate (BMR; also known as resting metabolic rate, or RMR) is the amount of energy the body uses to support the functions of the organs and physiological systems, and comprises approximately 60-75% of TDEE. The three organs most responsible for burning calories at rest are the liver, brain and skeletal muscle, which burn 27, 19 and 18 percent of the RMR, respectively. It's worth noting the brain alone uses about one-fifth of your RMR, which helps explain why you don't think