The 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 scientists at Keck Medicine of USC.

The research, published April 2, 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.

The takeaway for humans is that infant nutrition between birth and weaning is a critical period for healthy development, not just for future risk of obesity but also for 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,” Goran explained.

This metabolically dysfunctional fat could produce molecules and hormones that lead to systemic metabolic conditions including inflammation, Goran said. The next step in the research is to conduct a clinical trial in mothers and babies, he said.

Other researchers contributing to the study were first author Brandon Kayser, PhD, 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.

— Leslie Ridgeway