title: The effect of fasting and refeeding on oxygen consumption by rats.
abstract: 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.
authors.affiliation: Departamento de Fisiologia, Escola Paulista de Medicina, São Paulo, Brasil.
authors.forename: M A
authors.initials: MA
authors.lastname: Griggio
authors.forename: J
authors.initials: J
authors.lastname: Luz
authors.forename: S M
authors.initials: SM
authors.lastname: Carvalho
mesh_terms: D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology*; D004435:Eating / Q000502:physiology*; D004734:Energy Metabolism; D005215:Fasting; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology*; D051381:Rats; D013997:Time Factors