Effect of chronic caloric restriction: Physiological and behavioral response to alternate day feeding in old female B6C3F1 mice

Abstract

Physiological and behavioral performance was monitored in old (24 month) female B6C3F1 hybrid mice that were fed either a caloric restricted (CR) diet (60% of ad libitum) or fed ad libitum (AL). The CR group was fed (CR1) and then fasted (CR2) on alternate days starting at 12–14 weeks of age. The main objective of the study was to determine if the effects of intermittent feeding were different from those for daily CR feeding. The average daily body weight, body temperature, oxygen consumption per gram of lean body mass (LBM), and respiratory quotient were higher on the feed day (CR1) than on the fast day (CR2), whereas the average daily body weight, temperature, activity, and oxygen metabolism per gram of LBM were lower on CR1 than in AL. The daily range in temperature, oxygen metabolism per gram of LBM, and RQ was greater on CR1 and CR2 than in AL; the exception was RQ on CR1. No food was eaten on CR2, and water consumption was reduced by 60% compared to CR1. Average food consumption per meal, and average time eating and drinking per meal was greater in CR mice than in AL mice. The results of this study indicated that mice responded to alternate day CR by changing average daily metabolic output per gram of LBM in direct response to food consumption, whereas when CR mice were fed daily, no change was seen in average metabolism per gram of LBM. The fact that a significant reduction in energy output and temperature occurred in CR mice when metabolic pathways shifted from carbohydrate to fat metabolism may indicate that decreased glucose utilization may have triggered these CR-induced effects.