"It's obviously quite a conflicting message for kids who are selling these through their school but are told to eat healthily and exercise."
He said the promotion of energy-dense, nutrient-poor food such as hamburgers, fries and pizzas, had reached almost saturation levels through conventional advertising and indirect marketing.
The 2006/07 Health Survey found that 70 per cent of children between the ages of 2 and 14 years ate fast food at least once a week, 14 per cent ate fast food twice a week and 7 per cent ate it three or more times a week.
One in five New Zealand children was overweight, and one in 12 was obese, and those children were more likely to remain obese into adulthood, adding to the likelihood of future ill health and high treatment costs.
Diabetes-related medical costs have been estimated at $600 million a year - about 3 per cent of national health spending.
Mr Chester said indirect marketing such as sponsorship of charities or sports events by fast food giants had become an ingrained part of society and many people did not notice it happening.
It was part of a modern "obesogenic" environment where people relied on cars for travel, had sedentary jobs and passive forms of recreation with limited opportunities for physical activity, which promoted the over-consumption of food and drinks.
According to the paper, McDonald's sponsored more than 300 sports clubs and teams within New Zealand while Burger King was known for its sponsorship of the NZ Breakers basketball team.
A McDonald's spokeswoman said the chain assisted children in getting active and helped hundreds of thousands of Kiwi kids to play sport each year.
"McDonald's My Greatest Feat programme in 2010 saw 85,000 school aged children from across the country participate in a national pedometer programme, in support of the All Whites at the FIFA World Cup. We are proud of our support of activities such as these."
She said McDonald's had led the way in offering healthier options including in Happy Meals for children, a Weight Watchers approved menu range, or changing to a low saturated fat canola-based cooking oil.
"We've worked hard to ensure we can provide healthier choices for our younger customers, and now more than 50 per cent of our Happy Meals sold include a choice like fruit juice, water or apple slices."
Burger King marketing director Rachael Allison said while there was a role for fast food in a balanced diet, Burger King had decided not to sponsor children's sports teams or clubs and did not participate in school activities.
BACKING SPORT
Examples of sponsorship:
McDonald's:
Junior soccer and touch rugby
Olympic Games global sponsor
Variety, The Children's Charity
Burger King:
NZ Breakers basketball team
KFC:
2010 Black Caps Twenty20 cricket
KFC Grilled:
2011 NZ women's golf Pro-Am.