CO2 Output and Energy Balance of Hereditary Obese Mice

Abstract

The total CO2 outputs of young adult hereditary obese-hyperglycemic mice were measured over 2-day periods by means of the D2O18 method, and were found to be significantly higher than those of litter-mate controls. Since it had previously been postulated that the development of obesity in these animals was related in large part to a decreased total energy output, the energy balance of growing obese and normal mice was then studied. Food consumption, weight gains, and total CO2 outputs were determined at the ages of 6, 9 and 12 weeks. The CO2 outputs, which reflect the energy outputs, were of approximately the same magnitude for the two groups at 6 and 9 weeks of age, but were greater for the obese at 12 weeks. Food consumption remained nearly constant for both groups. An energy balance from these data is contrasted with one previously postulated by another group for similar mice.