We all know that Facebook is eating up our free time. But new research suggests that the social network may be making us fat and poor.

Facebook increases our self-esteem, which negatively impacts our decision-making skills and judgement, according to Andrew Stephen, associate professor at the University of Pittsburgh, and Keith Wilcox, associate professor at Columbia University. In turn, Facebook lowers our self-control and encourages negative behaviors like overspending and overeating.

The researchers found that more time spent on Facebook means higher credit card debt. Just five minutes of Facebook usage a day was proven to lower a user’s self-control, according to the study, which was based on an Internet survey of 541 American Facebook users.

Facebook surpassed 1 billion users worldwide in early October and is expected to see that figure double by 2014, according to some estimates. The average American spends eight hours a month on Facebook mostly due to boredom, according to a recent study. In America, 71.2 percent of Internet users are on Facebook, according to the social network.

Despite Stephen and Wilcox’s findings, the relationship between social networks and self-esteem is hotly contested. According to research published by Computers in Human Behavior, the 526 million people who log on to Facebook every day experience a self-esteem boost by using their profiles to construct how others see them. However, another study by a Ph.D. student in Stanford’s psychology department found that Facebook leads users to feel dejected and worthless when comparing their lives to those of their friends online.

Regardless of how Facebook makes users feel, Stephen and Wilcox’s study confirms previous research that has found that lower credit scores and credit card debt are strongly associated with poor self-control. In a 2001 survey, 40 percent of credit card holders blamed self-control problems on the widespread availability of credit cards, which increase our ability to overspend.

Nearly half of all Americans do not know what their credit score is, according to a survey of 2,200 people from CouponCabin.com. In September, the average American household had about $6,700 in credit card debt with U.S. credit card debt in 2011 totaling $46.7 billion.

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  • Thou Shalt Not... Act Like Bernie Madoff

    "You will not engage in unlawful multi-level marketing, such as a pyramid scheme, on Facebook." OK, so Facebook doesn't mention of Ponzi schemes specifically, but lying, cheating and scamming are definitely out. Leave the crookery to the pros on Wall Street and stick to raising pixelated chickens on your virtual farm. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Be A Convicted Sex Offender

    "You will not use Facebook if you are a convicted sex offender." 'Nough said. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Play Facebook God

    "You will not provide any false personal information on Facebook, or create an account for anyone other than yourself without permission [...] You will not create more than one personal account." No Facebook profiles for dogs, no automated bots, and no accounts for 2-month-old children. Hey, wait, we kind of like this rule. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Harass Thy Neighbor

    "You will not bully, intimidate, or harass any user." Cyberbulling has become a hot topic as social media usage continues to expand. In a recent U.K. court case, <a href="http://www.huffingtonpost.com/2012/06/08/nicola-brookes-facebook-cyberbullying_n_1580442.html" target="_hplink">Facebook was ordered to reveal the identities</a> of several bullies who had set up fake Facebook accounts to harass a 45-year-old mother. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Be Under 13

    "You will not use Facebook if you are under 13." Not a teenager yet? Sorry, no dice. <a href="http://www.huffingtonpost.com/2011/03/23/facebook-underage-users_n_839437.html" target="_hplink">In 2011, the chief privacy adviser of Facebook said</a> that an average of 20,000 underage Facebook accounts are shut down daily. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Spam Or Hack Facebook

    "You will not post unauthorized commercial communications (such as spam) on Facebook [...] You will not upload viruses or other malicious code." That means you, hackers and pushers of penis-enlargement pills. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Have Free Speech

    "You will not post content that: is hate speech, threatening, or pornographic; incites violence; or contains nudity or graphic or gratuitous violence." The lines blur a little with this commandment. While the policy is meant to curb inappropriate activity, opinion is split over what makes a post unsuitable. Perhaps surprisingly, if you were to compare <a href="https://twitter.com/tos" target="_hplink">Twitter's terms of service</a> with Facebook's, you'd see that Twitter currently has no policy on hate speech. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Post Thy Neighbor's Private Data

    "You will not post anyone's identification documents or sensitive financial information on Facebook." This one should be common sense. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Be A Digital Salesman

    "You will not use your personal timeline for your own commercial gain (such as selling your status update to an advertiser) [...] You will not sell user data [...] You will not sell, transfer, or sublicense our code, APIs, or tools to anyone." So basically, no, you cannot profit from Facebook unless Facebook's getting a cut. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>

  • Thou Shalt Not... Encourage Violation To These Rules

    "You will not facilitate or encourage any violations of this Statement or our policies." Whatever you say, Facebook. You've got the whole world in your hands. Taken from Facebook's <a href="https://www.facebook.com/legal/terms" target="_hplink">Statement of Rights and Responsibilities</a>