The determination of a person’s metabolic rate is of interest to both physicians and patients. The patient’s pretherapy metabolic rate (before diet and exercise therapy for weight loss) and during the two therapies is clearly relevant to the weight loss program.
The double labeled water method of measuring metabolic rate is the current research standard for determining metabolic rate.
It may in the future become useful in the the prescription and monitoring of weight loss therapy. From Reference (1):
The doubly labeled water (DLW) method is currently the most relevant, albeit expensive, method for measuring free-living energy expenditure in animals and humans. The DLW method is based on the exponential disappearance from the body of the stable isotopes 2H and 18O after a bolus dose of water labeled with both isotopes. The 2H is lost as water and the 18O as both water and CO2. After correction for isotopic fractionation, the excess disappearance rate of 18O relative to 2H is a measure of the CO2 production rate (1). This rate can be converted to an estimate of total energy expenditure by using a known or estimated respiratory quotient and the classical principle of indirect calorimetry (2).
(1) Doubly labeled water is a validated and verified reference standard in nutrition research. [PubMed Abstract] [Full Text HTML] [Full Text PDF] J Nutr. 2014 May;144(5):573-4. doi: 10.3945/jn.114.191361. Epub 2014 Feb 26.
(2) The AHA Recommends That Every Patient Have A Cardiorespiratory Fitness Evaluation Posted on December 6, 2016 by Tom Wade MD
(3) How And Why To Perform Cardiopumonary Exercise Testing – Resources From the American Heart Association Posted on December 8, 2016 by Tom Wade MD