Almost 15% of US households experienced a food shortage at some point in 2009, a government report has found.
US authorities say that figure is the highest they have seen since they began collecting data in the 1990s, and a slight increase over 2008 levels.
Single mothers are among the hardest hit: About 3.5 million said they were at times unable to put sufficient food on the table.
Hispanics and African Americans also suffer disproportionately.
The food security report is the result of an annual survey conducted by the US Department of Agriculture (USDA).
Households deemed "food insecure" experienced a period of inadequate food supply as a result of their economic situation, but did not necessarily remain without sufficient food for the entire year.
Although the number of food insecure households has risen sharply since the recession, the USDA says the growth rate has slowed, particularly toward the end of 2009.
The BBC's Katie Connolly, in Washington, says the results will be seen as somewhat surprising in a developed country that is also facing the problem of rising obesity rates.
Almost 60% of those experiencing food shortages were eligible for assistance to purchase food through a government food stamps program.
Since the recession, the Obama administration has expanded food stamp funding. In 2009, around 34 million Americans participated in food stamp programs each month.
Among those categorized as having "very low food security" - that is, those who experience the most severe food shortages - 28% of adults said that there were times in 2009 when they did not eat for an entire day because they could not afford to buy food.
Ninety-seven percent reported either skipping a meal or cutting the size of their meal for the same reason.
The report says that children in low food security households are often shielded from such behaviour by adults.
The prevalence of food insecurity has placed increased pressure on soup kitchens and community organizations to provide for the poor.
But Jeannine Sanford, the Deputy Director for Washington DC food pantry Bread For The City, warned against assuming that the problem of hunger would be alleviated when the recession ends because there are some groups whose conditions are virtually unaffected by the bad economy.
With its plethora of government jobs, Washington DC has not been as badly hit by the recession as other cities. Still, its soup kitchens and community organizations are struggling to keep up with demand - as they have been for some time.
Washington has long had a relatively large population of underprivileged people in need of assistance.
Ms Sanford says that the number of hungry people seeking help obtaining food has not changed much during the recession. Most of the people who come to her organization are the elderly, the disabled or those in minimum wage jobs who live well below the poverty line.
These people tend to live on fixed incomes, and have little hope of their income improving when the economy rebounds.
There were poor people in DC before the recession, and they will still be poor and need help when it is over, she says.
"The nature of receiving disability (welfare) is that the person is permanently disabled," Ms Sanford told the BBC. "It's not like the economy changes and that changes for them. They're still going to be trying to struggle on a really limited amount of income."