The latest Growing Up in Ireland study has found that 22% of Irish nine-year-olds are overweight or obese.
This survey, which tracks more than 7,500 children and their families, is the fourth in a series conducted by the ESRI and Trinity College Dublin that has conducted interviews at different stages in their lives.
Overall it paints a positive picture, with more than three-quarters of nine-year-olds in good health.
However, One-in-eight were coping with a long-standing health condition or disability.
Only a quarter of nine-year-olds reached the recommended level of physical activity which is at least 60 minutes every day.
15% of all nine-year-olds spent two or more hours watching TV or DVDs on weekdays.
Most children were a healthy weight but 17% were overweight and 5% were obese.
The study also found that 23% of nine-year-olds had an online profile, like a gaming or social media account.
Meanwhile, the children generally had positive attitudes to school - 62% said they always liked Reading; 48% always liked Maths but only 22% always liked Irish.