Development of obesity in diabetic mice pair-fed with lean siblings.

The role of hyperphagia -n the obesity of the diabetic mouse, C57BL/6J db/db, was investigated. Ingestion patterns and the amount of food for diabetic mice were controlled by yoking their food intake to that of nonobese siblings obtaining their food by bar pressing. Over a period of 6 wk, young (initial ages were 28 days) pair-fed diabetic mice accumulated 42% more body weight and approximately five times more extractable carcass lipid than did their siblings. Weight gain and absolute levels of carcass fat were reduced in food-restricted siabetic mice compared with dbs on unrestricted food intake. However, carcass fat as percentage of wet carcass weight was virtually identical in the restricted and unrestricted dbs (47.6% vs. 49.6%). From these results it is concluded that the heightened adiposity of the diabetic mouse does not require hyperphagia for its expression and thus represents a metabolic obesity.