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.

CONCLUSION

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.