Resting Metabolic Rate Test

DEXA SF offers resting metabolic rate (RMR) measurement to determine the number of calories the body burns at rest. The test uses indirect calorimetry — analysing oxygen consumption and carbon dioxide production through a short breathing protocol — to generate an accurate, personalised caloric baseline. This data is used to calibrate caloric intake targets for fat loss, muscle gain, or weight maintenance, and may complement a DEXA body composition scan to build a complete metabolic picture.

Resting metabolic rate (RMR) testing at DEXA SF uses indirect calorimetry, the reference standard for metabolic rate measurement in clinical nutrition and sports science settings. The protocol involves breathing into a mouthpiece or mask while at rest for a period of around 10–15 minutes, during which the device measures oxygen (O₂) uptake and carbon dioxide (CO₂) output. These gas exchange values are then used to calculate the respiratory exchange ratio (RER) and derive RMR via the Weir equation — providing a personalised estimate of how many calories the body burns at complete rest to sustain core physiological functions. The result is typically expressed in calories per day (kcal/day) and gives clients a far more accurate baseline than population-average formulas such as the Mifflin–St Jeor or Harris–Benedict equations, which use only height, weight, age, and sex and can deviate substantially from an individual's true metabolic rate. Individuals who have experienced metabolic adaptation from dieting, athletes with elevated lean mass, people managing thyroid conditions, or anyone who has found standard caloric guidance ineffective often benefit most from a direct measurement. At DEXA SF, RMR testing is positioned as a complement to the DEXA body composition scan. When combined, the two assessments provide a full metabolic baseline: the DEXA scan quantifies how much of the body is fat versus lean tissue and where it is distributed, while the RMR test reveals how much energy the body is expending to sustain that tissue. Together, these data points inform calibrated nutrition planning — whether the goal is fat reduction, muscle building, athletic performance, or general metabolic health optimisation. The clinical consultation included with every appointment at DEXA SF translates both sets of numbers into a practical action plan, including caloric targets, macronutrient splits, and a recommended retesting cadence to monitor progress over time.