Kai Ling Kong, PhD.

Kai Ling Kong, PhD, says that correlating differences in temperament with relative food reinforcement will help researchers identify ways to encourage healthier diets.

Study Explores New Ways to Identify Infants at Risk for Obesity

Published September 28, 2016 This content is archived.

story based on news release by ellen goldbaum

Babies who seem to get upset more easily and take longer to calm down may be at higher risk for obesity, according to a study led by Kai Ling Kong, PhD, assistant professor of pediatrics.


Babies who exhibit more “cuddliness” and calm down easily are less likely at risk.

“The research tells us that differences in behavior begin as early as infancy, and those differences can influence health behaviors that impact future health risks,” says Kong, the first author, who conducts research in the Division of Behavioral Medicine.

Fussier Infants Find Food More Rewarding

“We found that infants who rated higher on what we call cuddliness — the baby’s expression of enjoyment and molding of the body to being held — had lower food reinforcement,” explains Kong. 

“That means they were willing to work more for a non-food reward versus a food reward. So an infant who enjoyed being held closely by a caregiver was less motivated to work for food.”

Infants who rated high on how quickly they could recover from crying or being distressed also were less motivated to work for food compared to non-food alternatives.

Conversely, infants who rated lower on cuddliness and who took longer to recover from distress and arousal, had higher food reinforcement — that is, they were willing to work harder for a food reward.

Kong says that correlating these differences in temperament with their relative food reinforcement will help researchers identify ways to encourage healthier diets among the youngest individuals.

Parents who identify these characteristics in their infants also can benefit, she says.

Pressing a Button to Earn Rewards

In the study, 105 infants from nine to 18 months old were taught to press a button to earn a reward.

The infants completed the task twice, and they received either a piece of their favorite food as a reward or 10 seconds of a non-food reward — such as blowing bubbles, watching a Baby Einstein DVD or hearing music. Parents were instructed to say only specific phrases while the children completed the task.

As the task went on, it became increasingly difficult for the infant to earn the reward as they had to press the button more times. The amount of “work” they were willing to do was calculated by counting the number of times the child was willing to press the button to get the reward.

Assessing Infants’ Temperaments

Each child’s temperament was assessed through a detailed, 191-question online questionnaire that parents completed.

The researchers measured cuddliness by asking parents specific questions such as: “When being held, how often did your baby pull away or kick?” and “While being fed on your lap, how often did your baby snuggle even after they were done?”

Use Rewards Other than Food, Says Kong

“If a parent sees high relative food reinforcement in their child, it is not cause for immediate concern,” Kong says. Instead, she notes that parents can evaluate each child’s relationship to food and encourage the child to engage in activities other than eating, especially as a reward.

“Using rewards other than food, such as a trip to the playground or engaging in active play with their parents, may help reduce the child’s tendency to find pleasure in food,” she says. Making available a wide array of toys, activities and playmates so food isn’t the main focus and sole source of pleasure also can be beneficial.

Kong adds that children can learn healthier lifestyles when parents model healthy behaviors themselves, pay close attention to children’s satiety cues by noting when they are full and refrain from immediately using food to comfort a child who is crying or fussing.

Published in Childhood Obesity, Student is Co-Author

Infant Temperament is Associated with Relative Food Reinforcement” was published in Childhood Obesity.

Along with Kong, co-authors in the Department of Pediatrics are:

Other co-authors are Neha N. Sharma, PhD, a student in the medical education program, and Rina D. Eiden, PhD, senior research scientist at the Research Institute on Addictions.