Doubly labeled water technique

Doubly Labeled Water Technique for Determining Energy Expenditure Issues in Energy Nutiiticn Refetences Bibliography... 

DOUBLY LABELED WATER TECHNIQUE FOR DETERMINING ENERGY EXPENDITURE... 

The use of direct calorimetry is not a convenient technique, since it requires a specially constructed room and the confinement of human subjects for a day or longer in the room. The doubly labeled water technique offers a convenient alternative, providing that one has a machine to perform isotope ratio mass spectrometry. The doubly labeled water technique is used to measure the rate of total CO2 production in the body. This number alone is not sufficient to allow one to calculate the total energy expenditure. But the value for COj production (moles COi/day), along with the RQ, allows one to calculate the oxygen consumption using the following formula ... 

The doubly labeled water technique measures CO production, and not O production. Because the heal created per mole of expired CO differs between the three major fuels (carbohydrate, fat, protein), the calculation of energy expenditure requires a knowledge of the Lntemal fuel being oxidized. Thus, the doubly labeled water technique, coupled with infomnatior from RQ measurements, may be used instead of the method of indirect calorimetry (using an insulated chamber to measure heat production) to determine total energy production over the course of several days. 

Since the doubly labeled water technique can be used to determine total body water, the method can be used to estimate the fat-free naass, as defined in the Obesity chapter. In brief, with a knowledge of the amount of total body water, and the assumption that normal subjects have a fat-free mass that is about 73% water, one can calculate the amount of fat-free mass. Further details are in the Obesity chapter... 

Coran, M., Poehlman, E., and Danforth, E. (1994). Experiinental reliability of the doubly labeled water technique. Am. J. Ph-pioi 29, E510-E5I5. 

Dot blot lest, 218-219, 220, 290, 935 Double-isotope technique, calcium absorption by, 769 Double-stranded DNA,sffdsDNA Doubly labeled water technique, 303-305 DPA, see Docopentaenoicr acid Dnig nesislanee, in molecular clonittg, 946 Dry beriberi, 604, 606 dsDNA (double-stranded DNA), 13,34, 591,937,938... 

ATP calculation, 278-285 calculating energy expenditures, 297-299 bomb calorimeter 297-299 direct calarimefay, 300-301 doubly labeled water technique, 303-305 indirect calorimetiy, 299 energy nutrition, 305-306 metabolic rate, 301 -333 qbrsity and, 295,297 luspiratoty quotient, 274-305 units of, 274-276... 

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