Let's face it, two-thirds of the United States is overweight. Population studies conducted in the last decade suggest that environmental factors active during fetal development are of substantial consequence for the risk of developing metabolic and cardiovascular disorders in adulthood. The biological basis underlying this concept of "fetal programming" remains speculative but may involve permanent alterations in gene expression that may in turn modify tissue differentiation and hormonal and metabolic regulation.
Now a new animal study from New Zealand investigated the effect of the prenatal environment on programming of voluntary exercise. The researchers compared well-fed pregnant rats to those whose calories were restricted by 65 percent. They found that the rats born to mothers who had restricted calories exercised much less when they grew up and were more likely to be obese.
From this study, it would appear the prenatal environment can lead to the development of both abnormal eating and exercise behaviors, adding to previous research findings that the environment in the womb can influence physiological features of the metabolic syndrome.
This "hidden" variable may help explain why some people who follow all the "rules" of weight loss, like no grains or sugars and plenty of exercise, seem to still struggle with weight loss.
American Journal Regulatory, Integrative and Comparative Physiology. 2003 Jul;285(1):R271-3