Body mass, composition, and food intake in rabbits during altered acceleration fields

The effects of gravitational loading and unloading on body mass, body composition, and food intake were investigated in chronically accelerated adult male rabbits. The intensity of the acceleration field was increased by 0.25-G increments at intervals that permitted stabilization of body mass and food intake to a maximal field of 2.5 G. Control rabbits of the same age were maintained at Earth gravity under the same conditions of light and temperature. A negative rectilinear relationship was observed between body mass and the intensity of acceleration field. In spite of this, the decreased body mass appeared to be regulated, since centrifuged animals readily regained their lost body mass upon realimentation after a 3-day fast. At acceleration intensities above 1.75 G, ad libitum food intakes as well as maintenance food requirements increased with increasing acceleration fields despite a corresponding reduction in body mass. Analysis of body composition indicated a significant decrease in body fat and an increase in body water in animals adapted to a 2.5-G environment. Within 6 wk after the animals were returned from 2.5 G to Earth gravity, body mass and food intakes returned to the precentrifuged levels of corresponding control animals.