In the last few decades, Americans use credit (or debit) cards for more and more of our everyday spending. We’re also, collectively, becoming more and more obese. A group of researchers wondered: is there a correlation here? They conducted four experiments looking at what types of food people purchase when using a credit card, and what they purchase when using cash. They published their findings in the Journal of Consumer Research. The result is not surprising: people are more likely to buy junk food, on impulse, when paying with plastic.