than BMR due to thermic effect of feeding and residual burn from activities that occur throughout the day. Relationship between resting metabolic rate and energy expenditure Thermochemistry aside, the rate of metabolism and an amount of energy expenditures can be mistakenly interchanged, for example, when describing RMR and REE. Clinical guidelines for conditions of resting measurements The Academy of Nutrition and Dietetics (AND) provides clinical guidance for preparing a subject for RMR measures, in order to mitigate possible confounding factors from feeding, stressful physical activities, or exposure to stimulants such as caffeine or nicotine: In preparation, a subject should be fasting for 7 hrs or greater, and mindful to avoid stimulants and stressors, such as caffeine, nicotine, and hard physical activities such as purposeful exercises. For 30 minutes before conducting the measurement, a subject should be laying supine without physical movements, no reading nor listening to music. The ambiance should reduce stimulation by maintaining constant quiet, low lighting, and steady temperature. These conditions continue during the measurement stage. Further, the correct use of a well-maintained indirect calorimeter includes achieving a natural and steady breathing pattern in order to reveal oxygen consumption and carbon dioxide production rates under a reproducible resting condition. Indirect calorimetry is considered the gold-standard method to measure RMR. Indirect calorimeters are usually found in laboratory and clinical settings, but technological advancements are bringing RMR measurement to free-living conditions. Use of REE in weight management Long-term weight management is directly proportional to calories absorbed from feeding; nevertheless, myriad non-caloric factors also play biologically significant roles (not covered here) in estimating energy intake. In counting energy expenditure, the use of a resting measurement (RMR) is the most accurate method for estimating the major portion of Total daily energy expenditure (TEE), thereby giving the closest approximations when planning & following a Calorie Intake Plan. Thus, estimation of REE by indirect calorimetry is strongly recommended for accomplishing long-term weight management, a conclusion reached and maintained due to ongoing observational research by well-respected institutions such as the USDA, AND (previously ADA), ACSM, and internationally by the WHO. Common correlates to metabolic rate and 24-hr energy expenditure Energy expenditure is correlated to a number of factors, listed in alphabetical order. Age: Besides the epidemiologically correlated trends of aging, lowered physical activity, and loss of lean muscle mass, lessened cellular activity (the senescence thereof) may also contribute to lowering of REE. Work on non-human