Much has been made of the negative savings rate in the U.S. over the past eight quarters, and data from the Bureau of Economic Analysis (BEA) suggests that this spending gap may not be due to us overspending on things like high-end clothing and shoes, but rather that we're being squeezed by some other nasty addictions such as gasoline, our mortgages, and our prescription medications.

Love that luxury
Whether it's a $200-plus pair of True Religion jeans, a hot new purse, or a pair of specialty Nike running shoes, high-end goods these days can seem more like a necessity than a luxury. Outside of clothing, Best Buy (NYSE:BBY) and Apple (NASDAQ:AAPL), among others, have been racking up revenue from consumer spending on items like plasma TVs and MP3 players. Because of this, it's tempting to point to spending on luxury goods as a big contributor to the negative savings rate.

The problem with this argument is that while disposable personal income (DPI), which is total personal income from all sources minus taxes paid, has grown by around 5.3% annually over the past 10 years, spending on clothing and shoes has been growing at a considerably slower rate. Spending on some electronics, TVs in particular, has jumped in the last three years but has just matched DPI over the past decade.

So if not sweet threads and big-screen TVs, then what's emptying our pockets?

That oily hand in your wallet
Though oil prices are still very much in the forefront of market coverage from many sources, it's a less frantic atmosphere than it was last year when oil was pushing up around $75 per barrel. Consumers ended up spending slightly less in 2006 on oil and gasoline than in 2005, but we're still spending more than double today than we were 10 years ago. Overall, we now spend more on gasoline than we do on education by about $40 billion.

Compounding the high prices was the fact that Americans seemed almost wholly unwilling to give up their gas-guzzling ways. This appears to finally be changing, though, as the SUV craze is quickly moving toward a much more gas-friendly hybrid car craze. OK, well, more like an SUV-hybrid craze, but it's a start. While this is a step in the right direction, my best guess is that gas will continue to be a pain point for our wallets over the next few years.

Living a gold mine
The recent run-up in housing prices has many Americans feeling like they can run off to Jamaica and spend the rest of their days listening to old Bob Marley records and reminiscing on what it was like to have to work for a living. The flip side of that coin is that the amount of money that we're spending on housing has some of us feeling the pinch.

Annualized spending on owner-occupied homes was $1 trillion by the end of 2006, up 22% since the fourth quarter of 2003. That popping sound that's going on in various parts of the country and being echoed in the press means that growth will be hitting the brakes for the next few years. But given the fact that the housing market is relatively illiquid and sellers' emotions often play a big role in the selling process, it's unlikely that we're going to have a massive correction in the market as we did in the stock market back in 2000.

What this means is that housing could continue to squeeze our budgets for a few years while income catches up to what we're spending on our homes. Rental rates have been growing far slower than housing, but for many people, particularly families, this may not be a feasible alternative to owning a home.

Some sick health-care spending
I can't say that I was shocked to see how fast health-care spending has been growing, but the fact that 17% of our personal income now goes to health care was pretty eye-opening. To put that in perspective, the $1.6 trillion that we spend annually on health care is just slightly less than what we spend on our houses, clothing, and gasoline combined.

The demographics of health-care spending skews older, and as we dive deeper into the baby boomer retirement boom, growth in spending is likely going to continue to ramp up. Even for those of us not yet in need of lots of pricey medical services, health insurance, which is one of the fastest areas of growth in health care, is likely siphoning off a nice chunk of our bankroll.

It all adds up
You may not have that huge plasma TV adorning your wall or a $125 Ralph Lauren polo shirt on your back, but that doesn't mean that you may not have to think about tightening some budgetary screws. Many of the expenses that are claiming our extra dollars aren't easy to cut out. What this means is that in order to make sure enough is being socked away for retirement, Junior's college tuition, or just for that rainy day, we may have to get a little creative.

Of course, if anyone knows how to get financially creative, it's our Fools over at the Motley Fool Green Light newsletter service. But maybe you don't have to retire, do you?

Fool contributor Matt Koppenheffer tries to be more like the ant than the grasshopper and is already busy socking away savings in 2007. He owns shares of True Religion but does not own shares of any of the other companies mentioned. The Fool's disclosure policy is always there for you on a rainy day.