THE ROLE OF MOTOR-ACTIVITY IN DIET-INDUCED OBESITY IN C57BL 6J MICE/

Previous research in our laboratory has demonstrated that the C57BL/6J (B/6J) mouse has a predisposition to develop severe obesity if placed on a high-fat diet. In the present study we assessed the role of phys ical activity in this phenomenon. Obesity-prone B/6J and obesity-resis tant A/J mice were placed on one of four diets; high fat/high sucrose, high fat/low sucrose, low fat/high sucrose, and low fat/low sucrose. After 4 months, all animals on the high-fat diets had gained more weig ht than animals on the low-fat diets, and this phenomenon was greatly exaggerated in B/6J mice. Despite the fact that B/6J mice gained more weight than A/J mice on high-fat diets without consuming more calories , spontaneous motor activity was elevated in B/6J mice compared to A/J mice. There was no effect of the diets on activity either within or a cross strains. These data suggest that predisposition to diet-induced obesity is not explainable by reduced levels of physical activity.