Wellington, Sept 15 NZPA - Former Olympic and long-distance rower Rob Hamill says schools should sell healthy food to help kids achieve, rather than allow products that lead to obesity.

Hamill spoke at a Green Party event at the Beehive today before a 16,000-signature petition seeking the reinstatement of school food guidelines was presented.

The National Government dumped the guidelines in February saying schools would no longer be required to act as "food police".

The Government believed the rule was unnecessary and had caused confusion for schools, particularly around fund-raising and school events.

Green MP Sue Kedgley today said the Government complained about a "nanny state" but canning measures trying to reduce obesity, a main cause of ill health, was a "ninny state" approach.

The Obesity Action Coalition supported the petition saying nearly 21 percent of children under 15 were overweight and a 8.3 percent were obese.

Hamill said he was motivated to speak out as a dad. Hamill and wife Rachel's son Finn, aged seven, has just started school having been home-schooled until now. The couple have two other boys, Declan, aged five, and two-year-old Ivan.

"I want to see that when they go to school they have the right nutrition made available to them and are not offered the temptation of the high-fatty, high-sugary foods that ultimately don't do any good," he told NZPA.

While children could buy unhealthy food outside of school; "it doesn't mean you have to make that accessible at the school level," he said.

"It's an educational facility, it's about teaching excellence, striving to be the best that you are potentially able to be and it's an undermining process. It's suggesting that junk food is normal and healthy and OK by allowing it to be in the schools.

"I think it's really wrong, it's sending a bad message."

Alcohol or cigarettes were not sold at schools because of health problems but junk food was comparable, he said.

Apart from obesity-related health problems, Hamill said poor nutrition hurt kids' ability to learn.

In his sporting career he needed high quality fuel and children needed the same to achieve.

Ms Kedgley said many studies showed poor nutrition hurt educational achievement, with Pacific and Maori students especially vulnerable.

"Having scrapped the school food guidelines, schools are free to sell junk food such as fizzy drinks, chippies, donuts and sausage rolls and many are. Schools could also sell highly caffeinated energy drinks if they wanted," Ms Kedgley said.

"Why would we encourage children to eat food that we know is contributing to obesity, type 2 diabetes and dental decay? Unless we have government leadership on the issue, it will continue to be the staple food on sale in school canteens, and children will think it is the norm."

She questioned Health Minister Tony Ryall about the issue in Parliament.

Mr Ryall said the Government was spending $82 million over four years on its Kiwisport initiative to get youngsters to play sport and it was up to parents and school boards of trustees rather than the Government to decide what food was available at school.

"The Government will not be reinstating tuck shop controls," he said.