A new study of Australian children has found that almost 20 percent of kids are overweight or obese by the time they start school.
The study of more than 1200 children aged up to five conducted by the University of Sydney found that the biggest factor contributing to children's shocking weight gain was their home environment.
The study found that screen-time was a huge contributor to childhood obesity almost a third of overweight children were found to have a television in their room, and nearly half ate dinner in front of the TV more than three times a week.
Dr Louise Hardy who led the study recommended cutting down screen time and not rewarding children's good behaviour with sweets among steps parents could take to reduce childhood obesity.
More than 60 percent of both healthy and overweight children were rewarded with unhealthy snacks, with overweight girls the most likely to receive sweet treats in return for good behaviour.
"Kids are being rewarded for good behaviour with sweet food. They are drinking sugar in soft drinks and fruit juices and once these negative health behaviours are established, they're very difficult to change," Dr Hardy said.
"It may sound draconian, but why are we rewarding children for good behaviour at all?"
Dr Hardy also highlighted concerns for parents who were introducing bad habits so young without even realising their children were unhealthy.
"We asked parents whether they perceived their child to be overweight, healthy or underweight and found 70 percent of parents of overweight kindergarten children thought their kid was the right weight," she said.
"Thirty percent of the parents of obese children thought their child was the right weight."
The study also found that more than one-fifth of overweight and obese children did not eat breakfast, one of many lifestyle behaviours already established by the time children started school.
The researchers stressed the importance of getting these messages out to parents so that they would change routines in the home, such as eating breakfast and limiting screen-time, would give children the potential to start school in optimum health.
"The challenge for policy-makers would be to promote better health to parents of young children and influence household behaviour without being seen as promoting a 'nanny-state'," Dr Hardy said.
"It's a very difficult situation, but this is happening before children enter school and we need to get the message across while also not offending parents."