The CSIRO analysed more than 48,000 participants of its Total Wellbeing Diet to find those who claimed a reward under the program lost an average of 6.2 kilograms compared to a 4.8kg weight loss for those who didn't claim.

As part of the CSIRO diet, participants are offered up to $199 for successfully completing the 12-week program.

CSIRO research scientist and report author Gilly Hendrie said the results, released on Tuesday, showed personal accountability led to healthy weight loss.

"Breaking unhealthy habits that have developed over a long time can be hard and it is easy to lose motivation if you are not seeing immediate results on the scales," Dr Hendrie said.

"We've found self-accountability activities like tracking your weight and taking progress photos ... can give members the drive to stay on track."

The analysis also found two-thirds of people who claimed the refund lost more than five per cent of their starting body weight, compared to half of the non-rewarded members.

That sort of weight loss can reduce the risk of type 2 diabetes and cardiovascular disease.

Queensland participant Brian Thomas said the financial incentive was key to his 27kg weight loss.

"If I didn't have to track my food for the refund reward, maybe I would never have got into the habit of tracking," he said.

"It's allowed me to make positive changes to my own life and habits, and it has had a positive impact on my family."

Australians have received $2.2 million in refund rewards since the CSIRO Total Wellbeing Diet launched in 2015.

Australian Associated Press