Massey University Centre for Banking studies financial planning director Clair Matthews' research showed that both the youngest and oldest age groups were more likely to be in conservative funds.
"While this might be appropriate for the life-cycle stages of older investors, it might not be so appropriate for younger longer-term investors," Dr Matthews said.
Mr Foster said that the research brought home some of the concerns he had about the way the KiwiSaver default system affected younger savers.
With the exception of first-home buyers, who could withdraw their funds early, in three to five years, the large proportion of younger savers sticking with the default conservative option was a concern, he said.
"While some may have made the educated decision to stick with a conservative investment style, it is likely that many of these savers have simply chosen the 'path of least resistance' and not yet made a choice regarding their KiwiSaver investment," Mr Foster said.
Dr Matthews said younger investors were either staying in default funds allocated by their provider or lacked the knowledge and confidence to invest more aggressively.
She advised that all investors seek advice about the best choices for their individual circumstances.
With demographic characteristics playing such an important role in the choices people were making about KiwiSaver membership, it was important for gender, age, income and education differences to be acknowledged by the Government, advisers and providers.
"It means that KiwiSaver is not a 'one size fits all' option and it is important to manage its promotion and its structure to meet the varied needs of the population," Dr Matthews said.
Part of the research concluded that men were risk takers, even with their retirement savings, and likely to invest in aggressive and growth funds while women were more likely to choose conservative funds.
"Males are risk takers, whether it's in their choice of car or their investment fund. But when it comes to long-term savings, risk taking can actually be an advantage."
Dr Matthews also found that men were more likely than women to have previous savings when joining KiwiSaver.
More than half of male respondents said they had savings already while only 38% of women did.
The figures reflected and confirmed the difference between males and females in the level of interest they took in financial planning, she said. It was important for all New Zealanders to be better educated about their personal finances, but particularly so for women.
Those with bachelor and higher degrees, and those in households with a pre-tax income of $100,000 or more, were more likely to choose aggressive and growth funds.
