The Tip: Head to the ATM and withdraw a set amount of cash for the day and leave your credit card at home.

The Study: Cornell and Binghamton Universities

The Theory: Previous studies have found that, in general, we're more likely to overspend when paying with plastic because we can't see the physical money (cash) diminishing. Researchers at Cornell and Binghamton linked this phenomenon to our waistlines, theorizing that junk food purchases are often impulse purchases. When you have a set amount of cash withdrawn, you're less likely to blow it all on Snickers bars, soda and chips.