Americans who are fond of fast food fare such as hamburgers and French fries should brace their stomachs for a no burger day as workers from McDonald's and other fast food restaurants are set to join a nationwide strike on Thursday.

The protest is fast spreading to workers in the South and West Coasts as the employees demand higher wages and the right to unionise. They want a minimum wage of $15 an hour, almost double the current national minimum wage of $7.25.

Also expected to join the protest action are retail workers from major chains such as Macy's. The Thursday strike could affect up to 35 U.S. cities, the organisers said.

"These companies that own these fast food restaurants, they make way too much money off the backs of the employees," Time quoted Dearius Merritt, an employee of Church's Chicken in Memphis. He stressed that their wages are not enough to provide the needs of their families.

The unrest among fast food chain workers began in November 2012 in New York when 200 restaurant workers held a one-day protest. After seven months, the number of protesting employees had grown to several thousands across seven cities, including Chicago, Detroit and Kansas City, and has further spread to Los Angeles, Memphis and Raleigh.

Due to the recession, a growing number of fast food workers are main breadwinners, no longer teens whose numbers had gone down to 16 per cent of the total from 25 per cent 10 years ago.

Industrial and labor experts agree that it is difficult to support families based on their income levels, and that would cause the unrest to continue.

McDonald's said that implementing the $15 an hour proposal would kill jobs, while Burger King said 99 per cent of its chains across the U.S. are owned by franchisees who made independent hiring and firing decisions.

There are about 2.4 million fast food workers in the U.S.