The U.S. national debt, which is now over $19 trillion, means investors might need to save more money for their retirement, according to one expert.

"There's no doubt that the growing debt load and the aging demographics are disinflationary -- it keeps rates low and it keeps inflation low," said Brian Rehling, co-head of global fixed income at Wells Fargo Investment Institute.

Low rates cause headaches for savers. Gone are the days of a 5% yield on savings or money market accounts.

"This low-rate environment is at the detriment of savers," he said. "People essentially have to save even more for retirement because those low rates and low returns mean that they're not going to have as much in retirement as they may have in a higher-rate environment."

Rehling said low interest rates save the government plenty of money in interest payments. "Interest expense was 12% to 13% of the budget and we're now down to about 6% of the budget," Rehling said. "We spend less dollars today even though the debt is some three or four times bigger than it was 15 years ago."

Even though the Federal Reserve is looking to make its second rate hike since pushing short-term rates close to zero following the 2008 financial crisis, the increases will be small, making it unlikely that savers will notice a difference. Plus, the Fed has repeatedly told the markets that its plan to normalize policy will be gradual.

With low rates for the foreseeable future, Rehling said more people are taking on extra risk via the stock market and delaying retirement by working longer.

"You have to come up with some creative solutions when the market is just not going to give you those higher returns that may have been commonplace in the past," he said.

The low-interest-rate environment and trillions of dollars of central bank stimulus have led to a bull market that has spanned six years. The rally is still ongoing, with the major stock indices reaching multiple record highs in July.

Still, the low-rate environment is most painful for risk-averse investors whose only option for yield is stocks.

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