Over-feeding starts in babyhood, says Dr Liz Bragg
Nearly a third of five-year-olds in Wales are overweight, with 12.5% of children classed as obese, new figures from Public Health Wales show.
Merthyr Tydfil and Rhondda Cynon Taf have the highest number of overweight children, while the Vale of Glamorgan and Monmouthshire have the least.
The problem in Wales is worse than England and Scotland.
Health experts said the figures were "worrying" but children still had time to adopt a healthier lifestyle.
Radio Wales' Bethan Rhys Roberts spoke to Dr Liz Bragg, a paediatrician at Cardiff and Vale University Health Board.
Dr Bragg believes that even in babyhood, some parents are over-feeding children.