A University of Sydney study has found obese people who exercise between 6pm and midnight have a lower risk of death from cardiovascular disease and premature death.

The findings relate to vigorous physical activity in multiple stints lasting about three minutes, which the researchers believe is more important than overall physical activity.

They are quick to point out the findings are observational but say they build on smaller trials run in the past.

The research, published in Diabetes Care, was based on data from almost 30,000 people involved with the UK Biobank for eight years using wearable devices while exercising.

Participants were tracked throughout the day during any form of movement including walking, taking stairs, running and cleaning.

Some 12.5 million Australian adults are overweight or obese, which is about two thirds of the adult population, according to the Australian Institute of Health and Welfare.

Exercise physiology lecturer Angelo Sabag said overweight and obese adults were at risk of premature death and conditions including heart attacks and stroke.

“Exercise is by no means the only solution to the obesity crisis,” Mr Sabag said.

“But this research does suggest people who can plan their activity into certain times of the day may best offset some of these health risks.”

Senior author Emmanuel Stamatakis said further research needs to be done to establish causal link, however the findings offer useful insight.

“This study suggests the timing of physical activity could be an important part of the recommendations for future obesity and Type 2 diabetes management, and preventive healthcare in general,” Professor Stamatakis said.