It's only after the two-year old goes to bed that the chocolate comes out. "But when he's up I'll only give him one piece and I'll put the rest away," Maria Jofre, his mother, said.

With the latest data showing that almost two-thirds of Canberra adults and one quarter of children are overweight or obese, the ACT government is urging parents to set a good example.

In Ms Jofre's case, it's almost the other way around - the arrival of her son helped her establish healthy habits. "I'm much more of an outdoor person since he was born," she said. "He loves bushwalking, bike riding, being out at parks."

University of Canberra assistant professor in nutrition and dietetics Dr Gabrielle O'Kane refers to obesity as the "wicked problem" because it is so difficult to find solutions which halt its growth.

"The food environment has changed so much since the 1960s, food is ubiquitous, you can get it 24/7 from virtually anywhere you go," she said.

Labor backbencher Yvette Berry launched Good Habits for Life this week, a campaign targeted at children aged eight and below that provides tips for parents on how to role model healthier lifestyles to their children.

Dr O'Kane said that preventative programs which targeted children were the most effective way of reducing obesity rates.

"Adult obesity has continued to rise, but children rates have stayed stable for 15 years," she said.

"If we're making gains some gains with children, hopefully when they get older they maintain those eating habits."

The ACT has a goal of halting the rise in obesity, with a zero-growth-rate target.

"I think it's shocking when we look at the number of people in the community who are overweight and obese," Ms Berry, who has children aged eight and 11, said.

"This campaign is not about making parents and carers feel guilty about the things they can't do, but it gives them support and tips for things they can do."

Ms Berry's own strategy has been to declare Sundays for herself and her children as tech-free between 10am and 5pm.

"No iPads or phones - it's more a challenge for me than my son, but it's about making those rules and sticking to them," she said.

Dr O'Kane said education-only campaigns ultimately did little to change unhealthy behaviour.

"Our obesity rates are only getting worse over time without any improvement, but I'm not sure you'd expect them to improve because food marketing continues unabated and there's no control over any of that," she said.

"Whether it's making healthy foods cheaper or taxing unhealthy foods… these are the things that are going to make a difference."

Ms Jofre is supportive of regulation at schools, where she would not be able to necessarily control what her children would eat.

"I'd love to see a ban on fizzy drinks at school canteens and would love to see more healthy options," she said.

Dr O'Kane said that Canberra's proliferation of parks and outdoor spaces made exercise attractive to the average person but that improved services would also help instil healthier habits.

"We need to get people more into public transport and get them out of cars. Those little things make a difference," she said.

Mother of two Roni Rahman had no doubts about who the most important role model is.

"I think it's 100 per cent up to the parents. You can't rely on anyone else."