Fat and finances: You may not think these two things have a lot in common, but several studies suggest they do. Beyond making an investment in a gym membership, it turns out that the financial decisions you make could have an impact on your waistline. Here we look at some of the money moves that have been linked to weight gain. (For related reading, check out 22 Ways To Fight Rising Food Prices.)

IN PICTURES: 20 Lazy Ways To Save Money

  1. Charging It
    According to a recent survey released by Journal of Consumer Research, paying for grocery purchases with a credit - or even debit - card could have a negative effect on your choices. The study followed 1,000 shoppers over a period of six months and determined that not paying with cash was linked to more impulsive shopping purchases; in other words, junk food. The authors speculated that this may be because the "pain" associated with using actual cash may curb shoppers' desire to buy unnecessary (and less healthful) items. Plus, you can bet that if you put only the cash you need for your grocery purchases in your wallet and leave your cards at home, you won't be tempted to go over-budget.

  2. Stocking Up
    According to Consumer Reports, discount wholesalers like Costco and Sam's club really do have lower prices than regular retail stores. But stocking up on groceries once a month is not really a good way to go when it comes to your waistline. After all, the most diet-friendly food is the perishable kind (like fruits and vegetables), and while warehouse stores do carry produce and meat, there's only so much of that you can eat before it, well, perishes. That leaves packaged foods, and if you're worried about your weight, the last thing you need hanging around the house is a three-pound bag of potato chips.

    As well, according to a 2005 study that appeared in Obesity Research, visual cues affect not only how much a person is likely to eat, but how satisfied they feel. This means that the bigger the packages of food you buy, the harder it will be to size up a reasonable portion. (To read more about the pros and cons of shopping in bulk, see The Dark Side Of Bulk Buying and Buyer's Clubs: Will You Really Save?)

  3. Staying Too Lean
    Yes, spending $100 or more at the grocery store seems like a lot of money - but just try adding up what you spend if you don't. You're likely to be surprised by how much more you'll spend. Plus, grocery stores often offer coupons and sales - something you'll never find at 7-Eleven. Buying huge quantities of nonperishable food may be tough on your waistline, and if you buy too much, it may not even be good for your pocket book. But, on the flipside of the coin, you also don't want your cupboards to be bare. Otherwise, you're likely to find yourself starving in an empty kitchen and making impulse decisions on what to buy once again. Plan out some meals and buy the ingredients you need, and keep healthy snacks on hand at work and in your car - this way you won't be caught buying marked-up food at the gas station or convenience store.

IN PICTURES: 6 Generic Products That Are Just As Good

  1. Going Under
    Buying big quantities on a credit card may already be two strikes against your waistline, but they are also likely to land you in debt. And getting into debt is another financial move that can pack on the pounds. In fact, this is exactly what researchers discovered in 2009, when many families were struggling under the financial effects of the credit crunch. Writing in the BMC Public Health journal, German researchers determined that 25% of the 949 people in the study who were in debt were also obese, while only 11% of the 8,318 remaining participants were tipping the scales. Researchers suggested that being in debt increases stress and could affect weight by limiting access to leisure activities, reducing the amount of money available for healthful food and possibly also increasing the likelihood that a person will eat for comfort. (If you're in debt, find out how to get out in Expert Tips For Cutting Credit Card Debt.)

  2. Failing to Save
    If you're spending time counting calories, your time may be better spent counting your savings. A July 2009 article in the Journal of Epidemiology linked stress to weight gain, finding that people who reported higher levels of psychological stress were more likely to gain weight. Plus, a 2009 poll conducted by Reader's Digest pegged money as the greatest source of stress worldwide. If you don't have an emergency fund, don't stress about it - start one, now. (Are You Living Too Close The Edge? We provide some tips on how to put your finances on more secure footing.)

The Bottom Line
Studies suggest that while bad financial moves may not directly cause weight gain, the two things are related. Working to improve your financial well-being is not only a smart move for your money, but it is also likely to have a positive impact on other areas of your life - and perhaps even on your waistline.

Find out what happened in financial news this week. Read Water Cooler Finance: GM's Dramatic Return.