Health experts gathering in Dublin have urged the Government to act quickly to combat the issue.
Dr Muireann Cullen, manager of the Nutrition and Health Foundation, says the problem is "accelerating fast".
"We can see it in the statistics, in our children all the way to pre-school, that it's coming through," she said, adding that two out of every three adults in the country were either overweight or obese.
Dr Cullen told the health meeting any initiative had to be "Government-led". The Government had to be the "key leader" but the public also had a role to play and the problem needed to be stopped now.
The experts at the Dublin meeting urged all sections of society to work together to tackle the problem.
They were also addressed by Robin Shepper who previously worked as director of the 'Let's Move' campaign in the US, led by First Lady Michelle Obama.
She told the assembled experts there was no silver bullet. "It's a combination of things. Everyone has a role to play whether you're in government, the private sector, a parent, a grandparent," she said.
Earlier this year Dr Sinead Murphy from the childhood obesity programme at Temple Street Children's Hospital revealed that 31.8pc of seven-year-olds were either overweight or obese, which accounted for more than one in four schoolchildren.
She said the problem was beginning earlier and earlier in childhood.