The startling statistics on Canberra's obesity epidemic were revealed in the Chief Health Officer's report 2016, released on Thursday.

Nearly two in three Canberra adults are overweight or obese and those already considered obese are getting fatter, the report said.

Rates of obesity have ballooned over the past two decades, with the number of overweight or obese adults skyrocketing from 40 per cent in 1995 to 63 per cent in 2014.

Although obesity and overweight rates for children have remained relatively stable in recent years, eight out of 10 primary school and 88 per cent of high school students are not doing enough exercise.

"Over the past 10 years, the data about healthy eating habits for children has described a concerning picture," the report said.

The ACT government announced $2 million in this year's budget to encourage children to walk or ride to school.

Canberra children are also increasingly hooked on tablets, mobile phones, computers and televisions, with three quarters of high school children exceeding Australia's screen time guidelines.

But it's not all bad news and the report reveals Canberrans live the longest, smoke the least and immunise their children the most.

"I'm really pleased to say that we [are] a very healthy community ... we have excellent air quality, very clean water, great rates of immunisation, our rates of smoking have declined substantially but there are areas where we have more work to do," assistant health minister Meegan Fitzharris said.

ACT Chief Health Officer Dr Paul Kelly said the ACT continued to show good progress on the smoking front, with Canberra now boasting the country's lowest rate of daily smokers at 10 per cent.

The report also showed children were drinking less sugary drinks.

"As a mum to three young kids, I know it can be tough to monitor the amount of added sugar kids consume so I'm really pleased to see progress on this one," Ms Fitzharris said.

The report also found an increase in the number of Canberrans who reported being diagnosed with mental illness.

"It could be that people are more open, it could be that there are more mental health issues or more understanding of mental health issues. On the positive side, it may point to a lack of stigma of people being more open about it," Dr Kelly said.

"There are issues there and as the minister said there was quite a lot of money put aside in the budget for new mental health initiatives, which is important."

Cancer remains the leading cause of death in the ACT followed by heart disease, according to the report, which is released every two years.

Heart Foundation ACT chief executive Tony Stubbs said more work needed to be done to address obesity and overweight levels in the territory. He said it was pleasing to see an improvement in smoking rates.

"By and large, the Chief Health's Officer's report is very positive, I think we are quite a healthy city and probably leading the nation in a number of respects," he said.

"But I think we just need to make sure that we are still focused on the issues that are big in Canberra and clearly obesity is the one that has jumped up dramatically and the one we need to keep pushing and driving. It's another reminder that the health weight initiative is extremely important and we can't rest on our laurels on some of the successes we've had."