Food bank volunteers put in a "staggering" 4.1 million hours of unpaid work every year distributing food, fundraising and other duties, a new study reveals.
The value of the work has been estimated at £30 million a year if the volunteers were paid the national living wage, research found.
More than 700 independent food bank centres are now in operation, as well as the Trussell Trust's 1,235, with the number of people needing emergency supplies increasing dramatically as Universal Credit rolls out, said a report.
Professor Jon May of the Independent Food Aid Network (Ifan) said: "Ifan supports the efforts of the thousands of food banks, and tens of thousands of volunteers, working so hard to help feed their communities.
"But we call on Government to stop relying on food banks, and to accept its responsibilities for Britain's hunger crisis.
"In exchange for our financial contributions, Government is required to ensure sufficient support is available to all, so that no one needs to rely on charity to feed themselves or their families. That contract has been broken.
"Even as Government plan £12 billion in cuts to social security benefits by 2019/20, some of our largest companies continue to avoid paying their fair share in tax.
"Though we already pay £11 billion a year to subsidise a low-wage economy because employers are not paying people enough to live on, volunteers up and down the country are providing a further £30 million a year in 'free' labour to ensure that our fellow citizens in low paid work, on zero hour contracts, or relying on a broken benefits system have enough to eat.
"Whilst we must continue to support those in need, we must also advocate for fundamental change."
Samantha Stapley of the Trussell Trust, said: "It's astonishing to see a value put to the amazing and tireless work done by food bank volunteers up and down the UK.
"Without this vital community support hundreds of thousands of people would be hungry, and with nowhere to turn.
"But it is equally important to remember that whilst food bank volunteers do inspiring work, they cannot replace the welfare safety net.
"Issues with benefit payments remain the main reason why people need a food bank parcel, and with issues caused by Universal Credit increasingly reported by food banks as a concern, we urge the Government to take steps to make sure people don't face going hungry."
A Department for Work and Pensions spokesman said: "Reasons for food bank use are complex so it's misleading to link them to any one issue.
"We continue to spend around £90 billion a year supporting people, including those who are out of work or on a low income.
"Work is the best means of providing people with financial security, and with our welfare reforms people are moving into employment faster and staying there longer than under the old system."