- Click here for explanation of classification scheme.

• The table of nonprotein RQ that is currently universally used is the one proposed in 1901 and modified in 1912. Biochemical data on which the computations were made have been improved over the past decades; some inconsistencies can be found in the derivations of the values; therefore nonprotein RQ table should be slightly revised.

• Criteria for article inclusion not described.

• Criteria for article exclusion not described.

• Search procedures: Were based on historical tables printed.
• Was study quality assessed? Study calculations were assessed and refuted.
• Populations: that the calculations were made were considering healthy adults.

Outcome(s) and other measures

• Why type of information was abstracted from articles? Biochemical and physical data
• How was it combined? Data was not combined.
• What analytic methods were used? Atomic weights of carbon, hydrogen, and oxygen.
  Oxidation of glucose and fatty acid.

• # 18 articles included
• # of articles identified not addressed.

The earliest study was in German and printed in 1901 by Zuntz N, Schumburg H. Studien Zu Einter Physiologie des Marches. Who proposed the table of nonprotein RQ (and was cited by Williams, Richie, & Lusk in 1912 following a study of metabolism in a dog who ingested large quantities of meat).

The revised table by Lusk was corrected in 1924 in a paper titled, “Animal calorimetry. Analysis of the oxidation of mixtures of carbohydrates and fat. A correction.” There are 3 animal studies cited.

Current biochemical and physical data is based on studies reporting the average fatty acid composition of triacylglycerols from human adipose tissue. There are 5 primary research publications.

Eight textbooks representing the fields of physics, chemistry, nutrition, exercise physiology, and metabolism are used.

Table of Lusk (1924) 

Basic biochemical data required to generate a table of nonprotein RQ are:

1. Eqn of oxidation of glucose & representative fatty acid(s)
2. Energy potentials of glucose and representative fatty acid(s)
3. Volumes occupied by one mole of O₂ and CO₂ involved in the oxidation reaction under standard conditions (STPD). From these basic data, the volumes of O₂ and CO₂ involved in the oxidation rxn, RQ, & energy equivalent of oxygen can be computed for any given mixture of glucose & fatty acid substrates.

Energy combustion of fat

• Unable to trace consistency of Lusk table derivations: i.e., according to reference citations in original article, the energy equivalent of oxygen should have been either 4.946 kcal/l (STPD) or 5.030 kcal/l and NOT the 5.047 kcal/l (STPD) times 2.0182=9.457 kcal/g as computed by Zuntz and not explicitly written in Lusk’s 1928 paper. However, in the 1928 Table by Lusk, the energy value of fat was 9.384 for olive oil; 9.372/g for animal tissue fat, or 9.179 kcal/g for butter.
• Finally the quantity of CO₂/gram lard is mistaken; The RQ should have been 1.4289/2.0182=0.708 and not 0.707.

Current Biochemical and Physical Data

Based on implicit model of human triacylglycerol stores [or palmytoleyl-steroyl-oleoylglycerol (Frayn) or tripalmitorylglycerol by Ferrannini)], the weight average foumula is 272.4051 gram/mole.

The current model takes into account:

• 13 fatty acids represent 99% of fatty acids found in human triacylglycerols and are the respective average abundance
• 5 of 13 fatty acids in human triacylglycerols are known and represent 71.69% of the fatty acid stores. On the basis of this data, the energy potential is 9.7460 kcal/g.

Corrections to volume of gas that CO₂ and O₂ occupy:

• 1 mole O₂ occupies 22.3858 STPD
• 1 mole CO₂ occupies 22.2966 STPD

RQ of complete oxidation of a fatty acid =0.7036

• Energy equiv O₂=4.851 kcal/L STPD

Energy combustion of glucose

The RQ associated with the oxidation of glucose is 0.9960.

• Issues arise in the different values used for the energy potential of glucose.
• Ferrannini (1988): 673 kcal/m
• Lehninger (1981): 686 kcal/mole
• Weast (1989): 669.94 kcal/m

The current report uses 696.90 kcal/mole or 3.8683 kcal/g. Thus the RQ is 0.9960

Computation of the Table  

• For the extreme values of the RQ (0.7036 and 0.9960), the corresponding % of energy provided from glucose or fatty acid oxidation and the energy equivalent of oxygen are taken directly from balanced equations.
• For a given RQ between these two extremes, the values in the table cannot be easily interpolated because the relationships between the RQ and the % energy provided from glucose and fat oxidation, and the energy equivalent of oxygen are not linear.

Table of Nonprotein Respiratory Quotient (RQ)

Percentages of energy from
RQ	Glucose	Fatty Acids
0.7036	0.00	100.0
0.7050	0.50	99.5
0.7100	2.30	97.7
0.7150	4.20	95.8
0.7200	6.00	91.0
0.7250	7.80	92.2
0.7300	9.60	90.4
0.7350	11.40	88.6
0.7400	13.20	86.8
0.7450	15.00	85.0
0.7500	16.80	83.2
0.7550	18.60	81.4
0.7600	20.40	79.6
0.7650	22.10	77.9
0.7700	23.96	76.1
0.7750	25.70	74.3
0.7800	27.40	72.6
0.7850	29.20	70.8
0.7900	31.00	69.0
0.7950	32.70	67.3
0.8000	34.50	65.5
0.8050	36.20	63.8
0.8100	38.00	62.0
0.8150	39.70	60.3
0.8200	41.40	58.6
0.8250	43.20	56.8
0.8300	44.90	55.1
0.8350	46.60	53.4
0.8400	48.30	51.7
0.8450	50.00	50.0
0.8500	51.70	48.3
0.8550	53.40	46.6
0.8600	55.10	44.9
0.8650	56.80	43.2
0.8700	58.50	41.5
0.8750	60.20	39.8
0.8800	61.90	38.1
0.8850	63.60	36.4
0.8900	65.30	34.7
0.8950	66.90	33.1
0.9000	68.60	31.4
0.9050	70.30	29.7
0.9100	71.90	28.1
0.9150	73.60	26.4
0.9200	75.30	24.7
0.9250	7.69	23.1
0.9300	78.60	21.4
0.9350	80.20	19.8
0.9400	81.80	18.2
0.9450	83.50	16.5
0.9500	85.10	14.9
0.9550	86.70	13.3
0.9600	88.40	11.6
0.9650	90.00	10.0
0.9700	91.60	8.4
0.9750	93.20	6.8
0.9800	94.80	5.2
0.9850	96.40	3.6
0.9900	98.00	2.0
0.9950	99.60	0.4
0.9960	100.00	0.0

• Source: Peronnet F, Massicotte D. Table of nonprotein Respiratory Quotient: An update. Can J Sport Sci. 1991;16(1):23-29.

As stated by the author in body of report 

“Obviously, the differences between the Lusk table (corrected) and the proposed table are small and considered insignificant in the context of indirect respiratory calorimetry which may often entail large errors of measurement.

On the other hand, there is no apparent reason to continue using a table that contains systematic inconsistencies when it is as easy to use a table that is more consistent and in better accordance with biochemical and physical data currently accepted.

“Although the error is not great, yet it is worthy to note and of record (Lusk, 1924)”

University/Hospital:

Universite de Montreal (Canada)

• The strengths are that the authors provide a simple, yet thorough, physics and biochemistry description of how the Lusk nonprotein RQ table was developed.
• Calculations are accurate
• Weakness is that authors reference development of nonprotein RQ using animal data; also note the paper was published in 1991 so is over 10 years old.
• The findings are generalizable to healthy adults.