The findings, published in Pediatric Obesity, suggest infants who are fed high amounts of formula may form habits of overconsumption that lead to an increased risk of obesity throughout life.
Led by Professors Ben Gibbs and Renata Forste from Brigham Young University, USA, the study finds that clinical obesity at 24 months of age strongly traces back to infant feeding – with the team suggesting that encouraging a baby to finish their formula when full might do more harm than good – even though increased calories taken in are generally burned off.
"There seems to be this cluster of infant feeding patterns that promote childhood obesity," explained Gibbs.
Indeed, the researchers found that putting babies to bed with a bottle increased the risk of childhood obesity by 36%, while introducing solid foods too soon - before four months of age - increased a child's risk of obesity by 40%.
"Developing this pattern of needing to eat before you go to sleep, those kinds of things discourage children from monitoring their own eating patterns so they can self-regulate," said Forste.
"If you are overweight at age two, it puts you on a trajectory where you are likely to be overweight into middle childhood and adolescence and as an adult," he warned. "That's a big concern."
Study details
The researchers analyzed data from more than 8,000 families and found that babies predominantly fed formula were 2.5 times more likely to become obese toddlers than babies who were breastfed for the first six months.
However, the researchers noted that this pattern is not just about breastfeeding - reiterating that that moving infants on to solid food too early, or consuming food just before bed time also had significant effects on later obesity risk.
Forste added that when a child is full, and pushes away their bottle, they should not be encouraged to finish the rest of the bottle as this begins to form a habit of over consumption.
"Bottle feeding somehow changes the feeding dynamic, and those who bottle feed, alone or mixed with some breastfeeding, are more likely to add cereal or sweeteners to their infant's bottle at an early age, even before feeding cereal with a spoon," added Sally Findley, a public health professor at Columbia University, USA.
The next project for Gibbs and Forste is to re-evaluate the link between breastfeeding and cognitive development in childhood.
"The health community is looking to the origins of the obesity epidemic, and more and more, scholars are looking toward early childhood," Gibbs said. "I don't think this is some nascent, unimportant time period. It's very critical."