There are several factors which contribute towards a child's risk of becoming obese, but a major one is if the mother herself is obese, according to an article published in the Archives of Disease in Childhood (BMJ). Other factors, such as putting weight on rapidly during early childhood, and spending too long watching TV also play a role.

In this study, the scientists looked at 571 New Zealand children of European heritage. They were monitored at birth, than at the age of 3.5 years, and then again when they were 7. On each occasion their percentage of body fat was monitored. The scientists also noted how long each child spent, on average, watching TV, compared to how long he/she spent doing physical activity.

The authors found that a child who had accumulated a high percentage of body fat by the time he/she reached the age of 3.5 was significantly more likely to become an obese 7-year-old, compared to 3.5 year-olds whose body fat levels were normal. The risk of becoming obese also seemed to be higher for children who experienced rapid growth spurts.

The three most significant factors that contributed to a child's chances of becoming obese, the writers explained, were: 1. Having a mother who is overweight/obese. 2. Being a girl. 3. Watching too much television. In fact, the writers found that a child whose mother is overweight/obese generally has about 4% more body fat, compared to a child whose mother is not overweight/obese.

They also found that kids who spent three hours or more each day watching TV generally carried 5% more body fat than those who watched one hour at the most. Every additional hour of physical inactivity tended to add on about 1% of body fat, they explained.

Whether or not the explanation for their findings comes down to genes, lifestyle or what happened during pregnancy, the authors did not know.

They warn that children start of the path to overweight and obesity very early on in life. Hence, strategies to combat overweight/obesity should be deployed early too.

"Risk factors for obesity in 7 year old European children: the Auckland Birthweight Collaborative Study"
Nikki J Blair, John M D Thompson, Peter N Black, David M O Becroft, Phillipa M Clark, Dug Yeo Han, Elizabeth Robinson, Karen E Waldie, Chris J Wild, Edwin A Mitchell
Online First Arch Dis Child 2007; doi: 10.1136/adc.2007.116855
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