. Author manuscript; available in PMC: 2014 Jun 9.

Published in final edited form as: Front Biosci (Landmark Ed). 2014 Jun 1;19:967–985. doi: 10.2741/4261

Table 5.

Energy expenditure per kg body weight in male Sprague-Dawley rats (Charles River Laboratories) fed a low-fat or high-fat diet between 4 and 13 weeks of age¹,²

Diet	VO₂ (L/kg body weight/h)	VCO₂ (L/kg body weight/h)	RQ (VCO₂/VO₂)	Heat production (Kcal/kg body weight/h)
Low Fat	1.42 ± 0.013	1.30 ± 0.015^a	0.91 ± 0.004^a	6.91 ± 0.065^a
High Fat	1.41 ± 0.012	1.15 ± 0.011^b	0.82 ± 0.002^b	6.69 ± 0.058^b

See Table 2 for experimental detail. At 13 weeks of age, rats were placed in a computer-controlled Oxymax instrument (an open circuit calorimeter; Columbus Instruments, OH) to measure 24-h O₂ consumption and CO₂ production (34). Heat production is calculated according to the Brouwer equation (61): HP (Kcal) = 3.82 × VO₂ (in L) + 1.15 × VCO₂ (in L).

Values are means ± SEM, n = 16 rats/diet group. Energy metabolism data are expressed per kg body weight. In a 4-chamber calorimetry system, a 2-min measurement of O₂ consumption and CO₂ production is made for each rat at 8-min intervals for 24 h. The mean within each hour of the measurement is then computed, leading to 24 observations per rat for a day. Rat is the experimental unit in the statistical analysis.

^a,b

Means in a column without a common letter differ (P < 0.01), as analyzed by the unpaired t-test.