Scott DeFife, executive vice president of the National Restaurant Association, calls the protests a campaign "to disparage the industry," which he says operates on a tight profit margin. Doubling wages, he says, "would definitely have an impact on the creation of new jobs." He says it would be especially harmful for young people, for whom the jobless rate in some communities is already in the double digits.
Some fast food companies responded to the protests by saying they respect the rights of their workers.
And some who walked out used the media spotlight to talk openly about their financial struggles.
Kareem Sparks, a 30-year-old father of two boys, 6 and 12, was laid off in 2011 from a $17.50-an-hour city job in New York. His unemployment benefits ran out and he turned to food pantries. Five months ago, he found work at McDonald's.
"I'm grateful they gave me an opportunity to feed my family and put food on the table, but it's not enough," he says. Sparks supplements his income with a second job as a security guard, earning about $8 an hour. Together, he says, he brings home about $1,000-$1,100 every two weeks and needs food stamps to survive.
"It's horrible to know when I pick up my (McDonalds) check, it's going to be less than $200," he says. "You spend all your money in one store and go to sleep broke. It's not fair. Some people get their checks and don't come back to work."
The average hourly salary for fast-food workers was $9.00 in May 2012, according to the Bureau of Labor Statistics. The average age for these workers is 29 years old; for women, it's 32, according to the bureau. The restaurant association says its own analysis of Census data found that slightly more than 25 percent of fast-food workers are heads of households.
Both sides in the fight over the minimum wage cite numerous studies to buttress their arguments about whether a raise would be harmful.
The petition signed by the economists says that for decades, research has "found that no significant effects on employment opportunities result when the minimum wage rises in reasonable increments." The economists also note that minimum-wage workers employed full time for the entire year earn $15,080, almost 20 percent below the poverty level for a family of three.
But Michael Saltsman, research director at the Employment Policies Institute, cites another study that he says found raising the minimum wage was counterproductive -- with more people losing than gaining because hours were reduced and jobs were cut.
Tessie Harrell, one of the workers in the middle of this academic debate, walked off her job in protest last week.
As a Burger King manager in Milwaukee, Harrell, 34, has to stretch her $8.25 hourly salary to support five children (a sixth lives on her own). They live in a two-bedroom apartment. Her mother helped out financially and with child care, but she has since moved to a nursing home.
"It's not like we're teens working for a pair of shoes or a cell phone," Harrell says. "We're grown adults who can't find better jobs."
She would like to see something come from the protests, a wage improvement, even if it's not $15 an hour.
"I hope it works," she says. "We're just trying to survive and build a life for our children."