The three most significant risk factors for obesity among pre-school children have been identified.

According to a new study, inadequate sleep, having overweight/obese parents and having parents who restrict what a child eats in order to control their weight are the biggest risk factors for obesity among young children.

"We looked at 22 variables that had previously been identified as predictors of child obesity, and the three that emerged as strong predictors did so even as we took into account the influence of the other 19. Their strong showing gives us confidence that these are the most important risk factors to address," explained Prof Brent McBride of the University of Illinois in the US.

The researchers based their findings on the results of an extensive survey of parents, which provided detailed information on families. Participants were also visited in their homes by research assistants, who gathered further information and weighed and measured the participants.

According to the researchers, parents need to understand that their lifestyle and food preferences are being passed on to their children and that the taste of foods is established in the pre-school years.

"If you, as an adult, live in a food environment that allows you to maintain an elevated weight, remember that your child lives in that environment too. Similarly, if you are a sedentary adult, you may be passing on a preference for television watching and computer games instead of playing chasing games with your pre-schooler or playing in the park," they pointed out.

They also emphasised that restricting a child's access to particular foods will only make them want it more.

"If kids have never had a chance to eat potato chips regularly, they may overeat them when the food appears at a friend's picnic," they said.

The researchers encouraged parents to change the food environment in their homes by making healthy foods, such as fruit and vegetables, more easily available. Unhealthy options should not be available.

They also reminded parents that a child needs to be exposed to a food several times before they will even try it, let alone like it. Healthy foods should therefore be offered over and over again even if the child dislikes it at first.

The researchers also reminded parents to avoid using food as a comfort for their children if they are disappointed or hurt.

However, the Illinois team emphasised that the three main risk factors identified are ‘malleable'.

"They provide a road map for developing interventions that can lead to a possible reduction in children's weight status. We should focus on convincing parents to improve their own health status, to change the food environment of the home so that healthy foods are readily available and unhealthy foods are not, and to encourage an early bedtime," they said.

Details of these findings are published in the journal, Childhood Obesity.