Every aspect of life can influence one's state of wellness, so the saying goes.

However, number crunchers keen to determine to what extent, have come away with the rather stark claim that Australia's unhealthiest older citizens can expect their chances of entering a nursing home to double.

The study, the first to measure the individual and combined association of lifestyle factors with aged care admission, found the risk was most pronounced in those aged 60 to 75.

Using data from more than 127,000 men and women recruited to the long-term 45 and Up Cohort Study to investigate healthy ageing in NSW, researchers divided participants into three risk groups.

They were given healthy lifestyle scores out of 10, with up to two points each awarded in relation to five risk factors: smoking, physical activity, sitting, sleep and diet quality.

Based on statistical modelling estimates, the results were also investigated according to age and body mass index groups.

"Population ageing is one of the most significant social and economic changes affecting almost every country in the world," said study leader Dr Alice Gibson from the University of Sydney.

"Effective strategies to prevent or delay older adults entering nursing home care will help ensure society can adequately care for its increasing number of older people."

A quarter of participants were classified in the low-risk group after scoring 9-10 points, Dr Gibson said.

Some 62 per cent were in the medium-risk group (6-8 points) and 14 per cent in the high-risk (least healthy 0-5 points) group.

During a "follow-up" a little over 11 years further into the 45 and Up data, more than 23,000 or about 18 per cent of the subjects had been admitted to a home for the first time.

Compared with those in the low-risk group, the risk of nursing home admission was 43 per cent higher among those in the high-risk group and 12 per cent higher in the medium-risk group, Dr Gibson noted.

Those with the lowest lifestyle score (less than two out of 10) saw their risk of nursing home admission double compared with those with the highest scores (9 or 10 points).

Interestingly, the increased risk was slightly higher for the unhealthiest 60-64 year olds, while risk estimates were not altered by being overweight.

Four of the five lifestyle factors (the exception being diet) were associated with nursing home admission, which was highest among smokers.

Those with a current habit had a 55 per cent increased chance of admission compared with non-smokers.

The researchers said they hoped their work could be "a powerful motivator for many individuals to adopt or maintain a healthier lifestyle".

"Further, our findings may also incentivise government investment in preventative healthcare and health promotion given the greater cost associated with caring for people in institutions," they wrote.