Weinberg College
of Arts & Sciences

You Are What Your Grandmother Ate

If you’re overweight, your ancestors may be to blame. Researchers have found that our weight is influenced by what our mothers ate — as well as by the diets of their mothers, their grandmothers and their grandmothers’ others, quite possibly for many generations back. 

If your mother was malnourished as an infant, you were more likely to have been born underweight, anthropology professor Christopher Kuzawa says. And as an underweight baby, you would have had a greater-than-average risk of growing into an adult with high blood pressure and cholesterol. 

That, in turn, increased your risk of cardiovascular disease and diabetes, a trend Kuzawa has noticed in the Philippines, where he has been engaged in a 30-year longitudinal study on the effects of prenatal and early-childhood nutrition. Until recently, early-life malnutrition in that nation was common, and babies were often born underweight. Now those babies have grown into adults, and they’re eating more high-fat Western foods than their ancestors did. Their rates of diabetes and other cardiovascular diseases are climbing, a trend Kuzawa traces in part back to their mothers’ poor nourishment in babyhood and in utero. 

“Our findings add to the growing evidence that a baby’s birth weight is linked to the nutrition her mother experienced as an infant or young child,” Kuzawa said. “The mother’s own nutrition during infancy, and the grandmother’s while pregnant with the mother, predict the birth weight of the current generation”— to a greater extent, perhaps, than does the mother’s own diet during pregnancy. 

That’s not to say that a mother’s diet in adulthood has no impact. If your mother was obese while she was expecting you, your risk of being overweight and diabetic may increase slightly as a result. And if your mother then lost weight between pregnancies, your siblings may reap the benefit: studies have shown that obese women who lose significant amounts of weight tend to have children with lower body fat and cholesterol than siblings born before the weight loss.

Still, while obesity during pregnancy does put offspring at some degree of risk, Kuzawa’s findings in the Philippines suggest that an expectant mother’s diet may have less bearing on her baby’s size than the nutrition she received during her own months in the womb. 

The good news for mothers-to-be is obvious, according to Kuzawa: rather than following a strict “eat-this-not-that” pregnancy diet, they should focus simply on eating healthfully and well.

“The mother’s body seems to do a good job of buffering overall nutritional supply to her growing baby,” Kuzawa said. “Within the bounds of a healthy balanced diet, the overall quantity of food that a mother eats is unlikely to have large effects on her baby’s birth weight.” 

Our Evolving Diet

Would we all be healthier if we quit eating processed food and ate the way our ancestors did instead?

It’s a trendy notion these days, as evidenced by the popularity of the “Paleo diet.” Humans survived for millennia on nuts, wild plants and lean meat, the thinking goes, so those foods should be better for us than the sugar, dairy and grains we eat today.

That may be true, says Anthropology Department chairman and professor William Leonard, but there’s no need to go to extremes. Humans have, in fact, evolved toward “dietary flexibility,” and our ability to find or create food almost anywhere has allowed us to colonize the globe and thrive in many different environments.

Leonard says the Paleo diet is a narrow prescription for natural eating and adds that people can live healthfully on a wide range of diets, from mostly meat to mostly plants.