One in five Americans would rather spend today than save for tomorrow, a trend that could have devastating effects on those nearing retirement, according to a recent survey.

The warnings about saving and investing were issued by Natixis Global Asset Management after surveying 463 American investors with a range of investable assets from $200,000 to more than $1 million. Natixis, an asset manager with headquarters in Paris and Boston with $706 billion in assets under management, did the survey to determine attitudes toward saving and investing.

The number who would rather be the spendthrift grasshopper in the old story in Aesop's Fables rather than the frugal ant goes up as income goes down, with 22% of those with less than $500,000 in assets saying they would rather spend than save.

It might be fear that is preventing some from saving and investing as 47% of those surveyed say they have curbed both activities because of a fear of losing their money. "Steep market movements in the last few years have raised doubt among investors," the survey concludes.

Maybe for the same reason, 28% of investors rate their portfolios as risky, while 47% say they are neutral and 25% categorize them as not being risky. There is a divide among the sexes on this question with far more men (35%) rating their portfolios as risky than women (19%).

There is also a difference between the sexes on reasons for saving with more women (53%) than men (43%) saying the top reason to save is to take care of themselves and their families and more men (21%) than women (14%) saying the top reason to save is for asset growth.

Although it was a minority of those surveyed, Natixis finds it "especially troubling" that one in five of those over 50 say they do not know how much they should be saving to meet their future needs. This group of people will be retired for decades, says Tracey Flaherty, senior vice president of retirement strategies for Natixis.

"With the decline of retirement pensions, uncertainty about the future of Social Security and market volatility, Americans need, more than ever, to commit to a robust program of saving and investing," Flaherty says. "Planning for retirement is much more complex than it was a generation ago and far more important."

John T. Hailer, president of Natixis, says an effective retirement portfolio should be "durable (and) aim to limit risk in all types of markets."

He describes a durable portfolio as one that goes "beyond a traditional mix of stocks and bonds to include investments such as commodities, currencies and alternative mutual funds. The returns from these investments are designed so they do not move in lockstep with more familiar assets."

--Karen DeMasters