Understanding a person’s metabolism – the process in which the body converts food consumed into fuel to expend during all of its functions – is a key component to any successful weight/fat loss program. Resting metabolic rate (RMR) represents roughly 65% of all the calories a person expends during a day - keeping the heart beating, temperature control, breathing, and circulation activities.  Some people have a fast metabolism – one that effectively processes and converts the food you eat into energy, versus a slow metabolism that stores more of the energy from daily food intake. RMR, also referred to as basal metabolic rate (BMR) - is the total amount of calories that a human body requires to maintain itself.   Other metabolic components include the thermal effect of eating – the energy cost of chewing, digesting, and absorbing nutrients, which increases the RMR by 5 to 15%; physical activity expenditure – daily exercise - that adds another 15 to 30% to RMR; and non-exercise activity thermogenesis (NEAT), that represents walking, sitting down, getting up, and any restless-type activity. During my thirty years of multiple hospital-affiliated sports performance, fitness, and wellness programs, we measured a person’s RMR using a metabolic cart, which was also used to determine their ventilatory threshold and maximum endurance capacity – all factored into a client’s macro-nutrient intake and exercise guidelines to reduce excess weight and body fat, while preserving or increasing lean muscle.  There are equations that have been used to compare against the RMR measurements. Harris-Benedict (HB): Men: (13.75 x W) + (5 x H) – (6.76 x A) + 66Women: (9.56 x W) + (1.85 x H) – (4.68 x A) + 655Weight (W) is in kilograms Take your weight in pounds / 2.2 = weight in kilogramsHeight (H) is in centimetersTake your height in inches x 2.54 = height in centimetersA = ageThe main issue with the HB calculation is that it does not take into consideration your increase or decrease in lean body mass (muscle). A more accurate formula is the Cunningham equation:  RMR = 500 + (22 x LBM in kilograms). This formula requires obtaining a body composition from a DXA scan or the use of body composition devices, like bio-impedance, and skin calipers (less accurate with obese individuals). You divide your LMB in pounds by 2.2 to get kilograms. If you would like to learn more about metabolic rate, check out maxwellnutrition.com. You can also find information on other RMR formulas at  https://www.lizino.net/facts-about-resting-metabolic-rate/