Body weight change over the life span and longevity for C57BL/6J mice and mutations which differ in maximal body weight.

Body weights were obtained monthly for mutant groups with the C57BL/6J genetic background which differ in body weight (bg, c,J Ay, ob), and for a control group (C57BL/6J) (n = 16, N = 80). The mean longevity was significantly lower for all mutant groups compared with the mean longevity of the control group. Although obese mice (ob) had a shorter life span than other mutant groups, mice which also attained a very high body weight (yellow, Ay) did not differ significantly in longevity from thin mutant mice. Moreover, peak body weight was positively correlated with longevity for all mouse groups. All mouse groups showed a terminal decline in body weight except the albino group which gained weight throughout life. In general, long-lived mice obtained a greater terminal weight loss than short-lived mice within groups. The major finding of this study was that within each group there was a negative relationship obtained between growth rate and longevity.