Effects of intermittent feeding upon growth, activity, and lifespan in rats allowed voluntary exercise

Abstract

From weaning until death, male Wistar rats were housed in activity-wheel cages with 1 group maintained on ad lib (AL) diet and another provided the diet every-other-day (EOD). EOD-fed rats had a mean lifespan of 124 wk compared to 103 wk for AL-fed rats. While post-weaning body weight and growth rates were reduced among the EOD-fed animals compared to AL-fed animals, there was no significant difference in growth duration. Positive correlations were observed between lifespan and estimates of growth rate and duration in the AL group but not in the EOD group; apparently, growth rate is not inversely related to longevity. While the EOD feeding regimen resulted in higher activity levels later in life, wheel activity levels were actually lower in this group in early life compared to the AL group. The observation of reduced wheel activity among young rats fed EOD was replicated in a 2nd experiment. Apparently, increased activity does not mediate the beneficial effects of dietary restriction on longevity, unless this mechanism is active late in the lifespan.