Human total 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 ... 

TOTAL ENERGY EXPENDITURE OF FREE-LIVING HUMANS CAN BE ESTIMATED WITH THE DOUBLY LABELED WATER METHOD... 

The purpose of this article is to describe the theory of the H2 0 method, its assumptions, the analytical procedures and equations used in its calculation, and its validity compared to the energy balance method and indirect calorimetry when measuring the total energy expenditure (TEE) of humans. 

Schoeller, D. A., and HniUcka, J. M. (1996). Reliability of the doubly labeled water method for the mecisurement of total daily energy expenditure in free-living humans. /. Nutr. 126, 348S-354S. 

A study by Dulloo et al. showed that caffeine and catechins produced a thermogenic effect via sympathetic activation of NE, and that the effect of green tea extracts on the metabolic rate in humans is greater than that explained by caffeine content per se. In table 13.2, diurnal, nocturnal, and total 24 h energy expenditure values are presented for placebo, caffeine, and green tea extract. Diurnal energy expenditure... 

Fat. There is available little information concerning the human requirement for fat. Fat allowances must be based at present more on food habits than on ph3rsiological requirements. While a requirement for certain unsaturated fatty acids (the linoleic and arachidonic acids of natural fats) has been amply demonstrated with experimental animals, the human need for these fatty acids is not known. In spite of the paucity of information on this subject there are several factors which make it desirable (1) that fat be included in the diet to the extent of at least 20 to 25% of the total calories and (2) that the fat intake include essential unsaturated fatty acids to the extent of at least 1% of the total calories. At higher levels of energy expenditure, e.g., for a very active person consuming 4500 cal. and for children and for adolescent persons, it is desirable that 30 to 35% of the total calories be derived from fat. Since foodstuffs such as meat, milk, cheese, nuts, etc., contribute fat to the diet, it is necessary to use separated or visible fats such as butter, oleomargarine, lard, or shortenings to supply only one-third to one-half the amounts indicated. 

The requirement for choline is influenced by the amounts of methionine, folacin, and vitamin B-12 in the diet, plus the growth rate of the individual, the energy intake and expenditure, the amount and type of dietary fat, the type of carEtohy-drate eaten, the total amount of protein in the diet, and possibly the amount of dietary cholesterol. As a result, the exact human requirement has not been established. 

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