Inaccessible food cues affect stress and weight gain in calorically-restricted and ad lib fed rats.

Research suggests that caloric restriction (CR) is beneficial; however, the effects of CR in the context of food cues are unclear. A 2 (food cue vs. no cue)x2 (CR vs. ad lib) between-subjects design was employed to test these effects in 40 rats. It was predicted that cue exposure and CR would induce stress, and that these factors might interact synergistically. The results demonstrated that cue-exposed CR rats weighed less than did non-exposed CR rats. A blunted stress response was evident in CR rats relative to ad lib rats. Finally, cue-exposed rats had higher corticosterone levels and body weight during ad lib feeding than did non-cued rats. These results suggest that both CR and chronic food-cue exposure can be stressful, and the implications of this research are discussed in the context of humans' 'obesigenic' environment.