The effect of fasting and refeeding on oxygen consumption by rats
Griggio, M.A.; Luz, J.; Carvalho, S.M.
Brazilian Journal of Medical and Biological Research 25(2): 205-208
1992
ISSN/ISBN: 0100-879X PMID: 1339517 Document Number: 397527
Oxygen consumption is usually measured on fasted animals to avoid the thermal effect of feeding. However, fasting itself may decrease oxygen consumption as a way of conserving energy. The present study was undertaken to determine how long the fasting period should be to avoid the thermal effect of feeding without promoting a further decrease in oxygen consumption by the activation of energy-conservation mechanisms. Oxygen consumption was also measured to evaluate the effect of refeeding after different fasting periods. There was a 16% decrease in oxygen consumption from 0 to 12 h fasting related to the thermal effect of feeding, followed by a less intense (12%) decrease from 12 to 48 h fasting resulting from the energy conservation mechanism. During refeeding, oxygen consumption was higher during the first 30-min period than during the last 30-min period of the 1-h measurement, indicating the probable presence of a cephalic phase of postprandial thermogenesis. We conclude that 12-h fasting is the most appropriate period to avoid the thermal effect of feeding without significantly stimulating the energy conservation mechanism.