Changes in feeding efficiency and carcass composition in rats on repeated high-fat feedings.

Male and female Sprague-Dawley rats were fed ad libitum two cycles of 10 weeks of a high-fat (HF) diet, followed by 5 weeks of control chow (CH). During the initial 10 weeks (weeks 1-10) the HF fed male rats had an increased rate of weight gain and feeding efficiency (FE) in comparison to CH-fed controls. In the female HF-fed rats, the FE was higher during weeks 1-5 than that seen in CH-fed females. The male HF-fed rats had significantly higher levels of FE than the female HF-fed rats during the first 10 week period. At the end of the tenth week, the HF-fed rats weighed significantly more than CH-fed controls. HF-fed male rats gained more weight than HF-fed female rats. During the 5 week period (weeks 11-16) of CH feeding, the body weight of the HF-fed rats was reduced. At the end of week 16 there was no difference between the body weights of the CH and HF fed rats. During the second cycle of HF feeding (weeks 16-25) the HF-diet further increased body weight gain in both male and female rats compared with CH-fed controls. There was no reduction in FE in HF-fed male and female rats during this period when compared to the first ten week HF feeding period. After the last 5 week period (weeks 26-30) of CH feeding, the formerly HF-fed rats had similar body weights as the control rats, but still had more body fat than control rats.(ABSTRACT TRUNCATED AT 250 WORDS)