Obesity at childhood could damage the feet bones, leading to deformities, says a new study.
Each foot is made up of 26 bones, around 19 muscles, a large number of ligaments, tendons, blood vessels and nerves and is designed to absorb the shock of walking and running.
Excess weight and obesity can damage the delicate, immature nature of children's feet, leaving them at particular risk of deformities and abnormalities, said Stewart Morrison, a lecturer from the University of East London, who carried out the research found.
Researchers looked at 200 children from Glasgow aged nine to 12 years - 54 were obese and 15 were severely obese. Another 30 were overweight.
Obese children had feet that were up to 15 mm longer and seven mm wider than feet in normal weight children. In children with severe obesity, their feet were on average 18 mm longer and 15 mm wider, it said.
A second study of 44 nine-11 year olds, half of whom were obese, found that the obese children were unstable when they walked. They spent more time balancing on two feet when walking and less time on one foot than normal weight children. They also walked at a slower pace, it said.
"Obese children are less stable when walking and cannot walk efficiently," Morrison said.
He added: "The findings are interesting because previous research suggested that foot problems limit obese children's ability to take part in physical activity - so encouraging them to carry out exercise might not be the best thing."
"This typifies the problems of obesity, showing it affects every part of the body," Ian Campbell of the charity Weight Concern said.
Foot problems limiting the ability of obese children to exercise put them in a "catch 22 situation" because they need to be more active, he said. "This reinforces the need for prevention rather than cure, and for early intervention".