A new study has found that up to 23 per cent of babies in American Samoa are obese.
The research was conducted by Brown University in the United States and published in the journal Paediatric Obesity.
To conduct the study, researchers examined the medical records of nearly 800 American Samoan babies born between 2001 and 2008.
The team tracked the babies' growth, weight gain, and whether they were breastfed, given formula, or a mix of both.
Lead author Nicola Hawley says about 23 percent of boys and 16 per cent of girls in American Samoa are obese by 15 months of age.
"It was actually extremely shocking. We know that adult obesity the Samoas is particularly high - around 70 per cent of Samoan women are obese," she told Radio Australia.
"And so we expected that it might extend into childhood, but the levels of obesity we see in infancy are just so surprising."
Ms Hawley says maternal obesity is partly the reason.
"We know that there is a high level of overweight and obesity in women of child bearing age in Samoa, and we know that those women who are overweight and obese are the ones that tend to gain more weight during pregnancy, and they are also at risk of gestational diabetes during pregnancy."