The findings are from a national programme run by Public Health Wales, which collected information on the heights and weights of nearly 30,000 reception age children.
This is the first time we have had a clear picture of the how children in Wales are growing and although the headline figures are worrying, this is something that can be reversed.
We must have a response from all sectors in society including health, education and local communities themselves to ensure our children are able to adopt healthy lifestyles.
– Dr Ciaran Humprheys, Public Health consultant
I welcome this first report on the growth of children at school entry across Wales. Having good information is the basis for effective action on healthy child growth and to reduce childhood obesity. This report provides a baseline from which we can monitor our progress as a nation and more locally, into the future. Together, we must work for a healthy, active and resilient community in Wales where all children have the best start in life.
For the first time the heights and weights of reception children in Wales have been gathered and the results are worrying. Nearly 30 percent of five year olds are overweight and 12.5 per cent of children are classed as obese.
This prevalence is highest in Merthyr Tydfil (34 per cent) and the national figure for Wales is significantly higher than England, where 23 per cent of children are classed as overweight or obese.
A cafe in Cardiff sells this £17 breakfast meal - with eight sausages, eight rashers of bacon, six eggs, four beefburgers, hash browns, black pudding, beans, tomatoes, mushrooms, fried potatoes, omelettes, toast and four slices of buttered bread.
The owners say it's only a gimmick - but should the Welsh Government be looking into limiting portion sizes?
The people we spoke to, who were eating in the cafe, said tackling the obesity problem was instead down to education - and particularly down to parents at home.
We know that the ability to feed a family is driven by the price and availability of food and we know that many of the products high in sugar and salt are the cheaper products. There is no quick way in which we can turn that around but we do need to raise awareness of this and find alternative approaches.
Whilst I would hope any health improvements could be made voluntarily the law has a role in influencing the choices that we are making. I think the Public Health Bill is an opportunity to look at how we can do this.
Obesity leads to serious health problems, including heart disease, cancer, diabetes and high blood pressure.
We need to look at ways in which we can prevent obesity reaching epidemic proportions in Wales.
We are actively encouraging debate around health legislation as part of the current Public Health Green Paper Big Health Debate.