The number of families facing difficulties making ends meet has more than doubled in the last four years, according to the latest Growing Up in Ireland survey.
The survey of 7,400 children and their families, shows that 61% are struggling now, compared to 29% four years ago.
It followed the families of 13-year-old children, who were also interviewed when the children were aged 9, between 2007 and 2008.
The study also shows that children who develop weight problems by the time they are nine years old still struggle at the age of 13.
Up to 26% of 13-year-olds in the survey were deemed to be obese or overweight.
It also shows that more than half of those who were overweight at nine were still suffering weight problems at 13, while 40% had become obese.
Research Professor with the ESRI, James Williams, said only 10% of non-overweight nine-year-olds went on to be obese by 13.