Evolution, body composition, insulin receptor competition, and insulin resistance.
OBJECTIVE
Better understanding of the relationships between body composition and insulin resistance.


RESULTS
Average human adiposity and sarcopenia have attained unprecedented levels and the resultantly abnormal body composition distorts insulin receptor balance. Compared to evolutionary norms we now have too many adipocyte insulin receptors (in adipose tissue and liver) and too few myocyte insulin receptors. The body's insulin receptors can be conceptualized as competing for insulin molecules released from the pancreas. When an insulin molecule docks on an adipocyte receptor, substantially fewer glucose molecules are cleared from the blood than when an insulin molecule docks on a myocyte insulin receptor. Populational insulin receptor imbalance would seem to parallel the secular rise in insulin resistance and offers an attractive pathophysiological explanation for the accompanying type 2 diabetes epidemic.


CONCLUSIONS
An evolutionary perspective regarding body composition, insulin receptor imbalance, and the consequent impact on carbohydrate metabolism should enhance public acceptance of recommendations to increase physical activity.
Eaton
S Boyd
SB
Department of Anthropology, Emory University, 2887 Howell Mill NW, Atlanta, GA 30327, USA. sboydeaton@comcast.net
Cordain
Loren
L
Sparling
Phillip B
PB
D017667:Adipocytes / Q000378:metabolism; D050154:Adiposity; D005075:Biological Evolution; D001823:Body Composition; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology; D006801:Humans; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism; D008019:Life Style; D032342:Muscle Cells / Q000378:metabolism; D011972:Receptor, Insulin / Q000378:metabolism*; D012307:Risk Factors
D007328:Insulin; D011972:Receptor, Insulin