A US study has showed that children as young as four years old who experience stress eat more in the absence of hunger, beginning a cycle that could possibly mean extra pounds down the road.

Unlike previous cross-sectional research, this study from the University of Michigan focused on behavior over time. Researchers followed 207 low-income children from 2009 to 2015, recorded stress exposures and observed their eating behaviors.

The researchers define early life stress as chaotic home environments, and exposure to other negative life events, such as witnessing violence or trauma or experiencing material deprivation.

Children in poverty are extremely vulnerable to violence exposure, food scarcity and worry over limited resources. These stresses can result in neurobiological, cognitive, social-emotional, behavioral and physical health effects.

In the study, the researchers found that greater stress exposure correlated to increases in eating in absence of hunger and in emotional overeating.

"Kids who had higher levels of stress were observed to eat more in the absence of hunger and emotionally overeat more, as reported by their parents," said Alison Miller, associate professor of health behavior and health education at the UM School of Public Health. "Focusing on a pattern of eating as a stress coping mechanism in young children is important."

"These are small increases over time in eating behaviors related to stress during the period of childhood aged 4 to 7 years. What's salient is that children who eat this way very early in childhood may be at higher risk of having these small changes lead to weight gain over time, increasing health risk."

Miller said the public health response should be to screen for these risks at early life health appointments, address community issues like food scarcity, encourage physical activity, support parents so they can promote healthy habits, and work to improve stress regulation skills during childhood.