A few months ago, Mike Petree noticed an alarming pattern: His bank account would get uncomfortably low on the weekends before he'd get his paycheck, paid biweekly on Wednesdays.

Despite no changes to their daily habits, bills for him and his family of five skyrocketed: a $120 weekly grocery bill ballooned to $200, and a $50 gas tank refill doubled to nearly $100 per top-up.