"At the moment there's a lot of focus on what children should be eating and how much physical activity they should be doing and sleep, which is all really important.
"But what we don't really focus on is how the parents are providing food to their children - because it's all very well buying healthy food, but it's no good if the child doesn't eat it."
Children who had greater freedom over what they ate were more likely to be fussy eaters.
But children whose parents kept track of what they ate were less likely to be fussy, because the parents were varying their diet.
Surprisingly, the study, which involved about 1000 children, also found that parents who restricted food portions and stopped children from eating junk food more often had obese children.
"We don't know if parents who restrict what their children eat causes obesity," Dr Haszard said.
"There's been some experimental research that says children who are restricted at home, then go on to eat more when they're not in that restricted environment - but I think more probably it's more likely that a parent that has an overweight child is really concerned about their child's weight, they limit what their child is eating.
Children's poor oral health will also come under the spotlight this week, with an expert saying it affects their eating, sleeping and school work.
Professor Bernadette Drummond, of Otago University's dentistry faculty, who will address the conference tomorrow, said about 40 per cent of New Zealand 5-year-olds still got dental decay.
Inactive kids less fit than parents were
Today's kids can't keep up with their parents. An analysis of studies on millions of children around the world finds they don't run as fast or as far as their parents did when they were young.
On average, it takes children 90 seconds longer to run 1.6km than their parents did 30 years ago. Heart-related fitness has declined 5 per cent per decade since 1975 for children ages 9 to 17.
The American Heart Association, whose conference featured the research yesterday, said it was the first to show that children's fitness had declined worldwide over the last three decades.
"It makes sense. We have kids that are less active than before," said Dr Stephen Daniels, a University of Colorado pediatrician and spokesman for the heart association.
World Health Organisation numbers suggest that 80 per cent of young people globally may not be getting enough exercise.
Health experts recommend that children 6 and older get 60 minutes of moderately vigorous activity accumulated over a day. Only one-third of American kids do now.
The study was led by Grant Tomkinson, a physiologist at the University of South Australia. Researchers analysed 50 studies on running fitness involving 25 million children ages 9 to 17 in 28 countries from 1964 to 2010.
The studies measured how far children could run in 5 to 15 minutes and how quickly they ran a certain distance, ranging from 800m to 3.2km. Today's kids are about 15 per cent less fit than their parents were, researchers concluded.
The decline in fitness seems to be levelling off in Europe, Australia and New Zealand, and perhaps in the last few years in North America. But it continues to fall in China. In Japan, fitness had remained fairly consistent.
Dr Tomkinson and Dr Daniels said obesity likely plays a role, since it makes it harder to run.
- AP