Energy utilization in food-restricted female rats.
We studied changes in energy utilization in mature female rats exposed to varying degrees of food restriction. Food-restricted rats showed considerable energy conservation, exhibited primarily as a reduction in the energy required for daily maintenance. When a given body weight loss was produced by starvation (3 or 6 d), changes in body composition and energy utilization differed only slightly (and temporarily) compared with the same body weight lost by partial food restriction. All food-restricted groups demonstrated a remarkable ability to reduce maintenance energy costs and to achieve zero energy balance at food intakes 40-50% of controls. By contrasting these results with our previous work in food-restricted male rats, we identified possible gender differences in the response to food restriction. Females appear to preserve lean mass to a greater degree than male rats by utilizing relatively more fat for energy needs. This preference for fat as a fuel during negative energy balance suggests that females would lose less body weight for a given reduction in carcass energy than males, since fat is calorically denser than lean mass.
D000273:Adipose Tissue / Q000201:enzymology; D002001:Adipose Tissue, Brown / Q000201:enzymology; D000818:Animals; D001823:Body Composition; D001835:Body Weight; D004734:Energy Metabolism; D005260:Female; D005508:Food Deprivation / Q000502:physiology*; D008071:Lipoprotein Lipase / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013217:Starvation / Q000378:metabolism
D008071:Lipoprotein Lipase