It is common knowledge that genetics plays an important role in the risk for obesity. However, recent research highlights another important aspect of a predisposition to becoming overweight or obese: namely the nutritional status of mothers during pregnancy and nursing.
Part of the Global Obesity Summit, held recently at the University of Mississippi Medical School, addressed this issue. Dr. Barry Levin of the New Jersey College of Dentistry and Medicine presented research using an animal model that showed how the diet of dams (pregnant or nursing rat mothers) during the time period prenatal and perinatal can affect the later body weight of her offspring.
Just like people, animals become fat when they are exposed to the combination of high-fat high-sugar diets. What Dr. Levin’s work has shown is that some animals are resistant to becoming overweight when fed these diets — just like your friend who can eat anything in sight and never gets fat. In the animal models, you can selectively breed these fat-resistant rats and the fat-prone rats.
Interestingly, if you take the pups from the skinny dams and have them nurse from the fat dams and vice versa, the pups that were supposed to be fat resistant based on their genes become fat prone and the pups that were genetically predisposed to become fat become fat resistant. Thus, that simple “it’s just genetics” explanation does not hold up. It seems that what happens very early in life also has a profound effect on later susceptibility to obesity.
Looking at this and other research, it’s logical to conclude that some of the differences with regard to a child’s future body weight may take place based on what the mother eats during pregnancy and while she is nursing.
One famous study, Obesity in Young Men after Famine Exposure in Utero and Early Infancy, looked at the sudden rise in obesity rates in The Netherlands after famine during World War II. Mothers who had gone through extreme starvation early in pregnancy were found to have severely obese children. If the mothers had been starved later in pregnancy, the children were more likely to get diabetes later in life.
There are some plausible mechanisms that have been proposed on how the nutritional status of the mother could affect the developing fetus. For example, development of stem cells that will become neurons in the parts of the brain involved in hunger and fullness, especially in the hypothalamus, are known to be affected by the mom’s nutritional status.
This new area of research on how what mothers are eating during pregnancy may affect children’s later weight status just adds one more factor in the nature nurture discussion.