We have known for a while what a mother eats or drinks may have a profound effect on a developing baby for the rest of the baby’s life. For example, we know how women who drink alcohol throughout pregnancy have children with fetal alcohol syndrome, a disorder with permanent birth defects. However, when a child is born with this disorder, the signs are obvious in the baby.
However, in 2003, several scientists hypothesized that a child may be predestined to be an overweight couch potato if the mother was undernourished while pregnant. This hypothesis is unique in that it suggests that not only will under-eating create a child with a metabolic disorder (obesity, metabolic syndrome, and/or diabetes potentially), but it will also create a behavioral change in the baby’s adult life (sedentary).
A study published in the 2003 July edition of the American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, investigated the effect of the maternal environment on creating sedentary behavior after birth, into adult life in rats.
Two separate studies were used. The researchers found that in the first study, rats that were undernourished in the womb were significantly more sedentary than those born of mothers with a standard diet. Overeating was more common in mature rats that had been exposed to maternal undernutrition.
The researchers wanted to also see if a hypercaloric diet in the offspring would affect the offspring’s behavior, and, not surprisingly, overeating (hypercaloric eating) exacerbated the rat’s tendency to be sedentary.
Importantly, in the rats tested at approximately puberty, sedentary behavior was already present before the development of maturity-onset obesity and was found significantly more in males compared with females.
In the second study, rats of undernourished mothers were maintained on a normal diet after weaning, and their behavior was studied only at 14 months of age. These rats were shown to be significantly more sedentary than offspring of normally fed mothers. A gender difference occurred, with males significantly less active than females, but a “prenatal effect” of sedentary behavior was significant in each gender. The authors concluded that this second study, in conjunction with the first study, suggests that the sedentary effect is persistent through life, is solely related to prenatal maternal diet, and occurs in both genders.
They conclude that 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 research raises the intriguing possibility that some behaviors and lifestyle choices that exacerbate the metabolic syndrome in humans are an inherent part of the syndrome and may have a prenatal origin.
The implications of this hypothesis are profound! If sedentary behavior and overeating are determined during prenatal development, this may explain why public health attempts to improve exercise and to reduce food intake in adults with hypertension, insulin resistance, and hyperlipidemia are often ineffective.
Since this study, the same authors have performed another study with the same results, but it also showed that the mechanism may be at the genetic level, such that under eating actually affects how the genes are expressed after the baby is born.
It appears as if the mother introduces a feeding environment to the baby and conditions the baby to “expect” a certain amount of food. However, when the food is found in abundance or more than what their metabolism can handle, there are metabolic negative consequences.
However, both of these studies involved mother-rats who were under eating. But what about mothers who might overeat: Is this associated with adult-onset obesity?
Research results presented at the 10th International Congress on Obesity in 2006 showed that overeating during pregnancy may have significant and numerous health impacts on an unborn child. The research demonstrated that the offspring of mothers who overeat with a high-fat diet are at risk for liver and pancreas damage. Both of which can contribute to early-onset obesity and diabetes. In addition, significant brain changes can occur. These changes take place in the hypothalamus, the region of the brain that controls weight regulation. The data suggest that children born to mothers who eat a high-fat diet may be predisposed to weight problems.
I did not find anything investigating if overeating mothers may affect an offspring’s behavior. However, that could just be a matter of time before those results are published.
It must be noted that the studies I described above should be viewed as “associations” and not “cause-and-effect.”  There are too many other factors that are also involved in the causes of obesity, diabetes and other metabolic disorders.
Clearly we have much more to learn, but the data strongly confirms the importance of a well-balanced diet for pregnant women.
There are many more unanswered questions: What if a mother changes her diet while pregnant? What affects will that have and does it matter when the mother changes her diet? What is the ideal diet composition? Could there be a paternal nutrition role? These are only a few of the many questions that still need to be answered.  
Thus far, the evidence in human studies is lacking.
In Summary
The take home message here is a well-balanced diet is very important for the mother’s health during and post-pregnancy and her baby. Her diet can affect her own weight, the baby’s delivery weight, the baby’s long-term health and likelihood for disease. The studies above suggest that even a baby’s behavior may also be affected prior to any abnormal metabolic disorders starting. When and what are the exact eating conditions that triggers these disorders is still unanswered. 
For now, because we know there are many causes for an assortment of diseases related to maternal nutrition, further research is needed to determine the definition of “a well-balanced diet” that may prevent any of these diseases from developing in a baby’s body. 
If you have any more questions, please email me at scott@focusedtrainers.com.
Until next time…