Early origins of obesity: programming the appetite regulatory system

An article in The Journal of Physiology presents important research showing that events before birth can permanently change patterns of appetite and fat deposition in child and adult life.

A collaborative effort headed by Prof I. C. McMillen, of the Centre for the Early Origins of Adult Health at the University of Adelaide, Australia, and Dr C. L. Adam of The Energy Balance and Obesity Division of the Rowett Research Institute, Aberdeen, is shedding new light on potential causes of child and adult obesity. This research forms part of an exciting new area of physiology, the early origins of adult disease, which is beginning to unravel some of the mechanisms by which events which occur during the development of an individual can permanently affect postnatal physiology.

This paper reviews evidence from a series of studies which have shown that there are robust associations between the prenatal experience and patterns of fat deposition and appetite regulation in postnatal life. Both epidemiological studies across large sectors of human populations in a large number of countries, and animal models in which the prenatal environment has been artificially manipulated, have shown that prenatal exposure to either an increased or decreased levels of nutrition before birth leads to an increased risk of obesity in postnatal life.

Building on the strong foundation of studies linking prenatal exposures to patterns of postnatal feeding behavior, these researchers have addressed the question, to what extent the fetus has a functional capacity for regulating its appetite. Dr McMillen and Dr Adam have been the first to demonstrate that the fetus possesses all the components of the appetite-regulating system before birth, and that increases in nutritional supply are able to regulate the expression of these components.

An up and coming researcher in this field and coauthor, Beverly Mühlhäusler, says: “The concept of a fetal appetite is a difficult and intriguing one. What our research suggests is that all the components of the system which we know regulates appetite in postnatal life are already there before birth and may be responding to signals of nutritional status. This, of course, raises the possibility that changes in the fetal environment can permanently change the way that this system develops and result in changes in feeding behaviour after the individual is born.”

With child and adult obesity currently at epidemic proportions in both the developed and developing world, this research offers new and important insights into the causes of this complex disease.