MENLO PARK (CBS SF) — Spending time on Facebook could leave users with an increased waistline and decreased self-control, according to a new study.

The Columbia Business School and the University of Pittsburgh studied the effects of heavy use of the social media site, finding that social networking sites like Facebook may increase self-esteem, but that could lead to users “rewarding themselves with something hedonic and indulgent.” according to the study.

Social media was linked with higher body mass index, and higher credit card debt.

“Even after just five minutes of Facebook use, people showed higher levels of self-esteem and a reduction in observable self-control,” said Andrew Stephen, assistant professor of Business Administration at the University of Pittsburgh Business school.

The research will be published in the June 2013 edition of the Journal of Consumer Research.