The report also showed that the number of homeless families in Philadelphia increased by 1 percent over the last year. The number of homeless individuals stayed the same, the report found.
On any given day, Philadelphia has more than 5,000 homeless people, city officials said.
The city is home to more than 400,000 people living in poverty, a rate of nearly 27 percent, census figures show. Many thousand more live on low incomes in difficult conditions, antipoverty advocates say.
Wynn, angry about the increased level of need for food, said the survey, conducted between September 2012 and August 2013, does not take into account the nationwide cut in food stamps on Nov. 1. Still more cuts to the program are expected, as both houses of Congress have called for diminished funding of food stamps in the coming years.
Wynn predicted that the cuts will stretch pantries to their limits and beyond.
"Without enough food to eat, we're going to have children who won't be able to count to five," Wynn said. "They won't develop appropriately physically and mentally.
"Somewhere in the last 20 years, we decided that the poor aren't important. The core principles we Americans were raised on are gone. 'It's all about me, and why should I care?' people say."
Philanthropy cannot fill the hole of need that hungry people face, said Eva Gladstein, executive director of the Mayor's Office of Community Empowerment and Opportunity.
"With federal resources diminishing, you don't make that up with grants here or there," Gladstein said.
The conference report also showed that 55 percent of people needing food assistance in Philadelphia have jobs, while 28 percent are elderly.
Food pantries and emergency kitchens have had to turn people away due to lack of resources, the report said.
The median household income in Philadelphia is $36,957, according to the report. The median income nationwide in 2012 was $51,017, according to the census.
The 25 cities in the report were chosen because their mayors are part of a task force on hunger and homelessness.
Of the cities, which include Los Angeles, Boston, Washington, San Francisco, and Trenton, only Cleveland has a lower median household income ($27,470) than Philadelphia. And only Providence, R.I., has a higher poverty rate.
Philadelphia has the highest rate of poverty among the 10 largest cities in the country, census figures show.
Regarding the homeless, Philadelphia is on a spectrum of "holding steady to making progress," said Roberta Cancellier, deputy director of Philadelphia's Office of Supportive Housing.
"We're focusing on getting people into affordable housing," she said.