Loss of body weight, during later stages of aging, is a phenomenon rec
ognized in all human populations studied. Reduction of body weight is
accompanied by a loss of internal organ weight and volume. The usual a
pproach is to describe organ weight versus age. However, organ weight
can be related to overall body weight, by means of the allometric equa
tion. This general expression can be used to relate the weight of each
of several organs to that of the body, and offered a good description
of data for a reported Japanese autopsy study on males and females ov
er the age of 60 years. The equations were also used in describing the
ratio of organ weights (such as the spleen/liver weight). A further e
xtension was in examining the terms of the allometric equation (a cons
tant and an exponent for each organ), and noting a close coupling betw
een male and female values. The allometric description of organ weight
s versus body weight, suggests a 'co-ordinated involution', and appear
s worthy of further investigation.