Study indicates that overfeeding babies between birth and weaning may lead to development of “unhealthy” fat

Long-term risk for obesity and its complications, including Type 2 diabetes, may be established during a critical period between birth and weaning, according to research by scientists at Keck Medicine of the University of Southern California (USC).

The research, published April 2, 2015, in the peer-reviewed journal Public Library of Science (PLOS) One, demonstrates that mouse pups from smaller litters – with more access to nutrition – developed more unhealthy, inflamed fat. When these animals were placed on a high-fat diet in later life, they developed an obesity profile that was more indicative of risk of obesity-related diseases such as Type 2 diabetes and fatty liver disease.

The takeaway for humans is that infant nutrition between birth and weaning is a critical period for healthy development, not just for future obesity risk, but also for future risk of obesity-related diseases later in life, said Michael I. Goran, PhD, corresponding author and professor of preventive medicine, physiology and biophysics and pediatrics, Keck School of Medicine of USC and director, USC Childhood Obesity Research Center.

“The human translation would be a parent overfeeding his or her baby, giving the baby more formula or other sugary beverages in the bottle, to keep the baby happy, or to get the baby to sleep,” he said. “We found that over-nutrition early on primed the fat in the mice to be more dysfunctional. They gained the same amount of fat as mice in larger litters, but the fat they gained was more metabolically dysfunctional.”

“Metabolically dysfunctional” fat could produce molecules and hormones that lead to systemic metabolic conditions including inflammation, Goran said. Scientists don’t know yet what causes the dysfunction, but it is known that about one third of obese Americans have more inflamed fat, which could be attributed to the way it develops in early life, he said.

The next step in the research is to conduct a clinical trial in mothers and babies, he said.

Other Keck School faculty researchers contributing to the study include first author Brandon Kayser, PhD, a postdoctoral fellow at the Institute for Cardiometabolism and Nutrition, Paris, France, and Sebastien Bouret, PhD, associate professor of pediatrics, who is at the Saban Research Institute at Children’s Hospital Los Angeles.

The research was supported by the Dr. Robert C. and Veronica Atkins endowed chair funds, the National Institutes of Health (grants R01DK84142, P01ES022845), the United States Environment Protection Agency (grant RD83544101) and the European Union FP7 integrated project (grant agreement no. 266408, “Full4Health”).

by Leslie Ridgeway

For a copy of the study, go to