American buying habits are partially to blame, said Jones. "People buy … things they're not used to buying. Let's say you're in the store ... and you see something that makes you think, 'Oh, wow, that'd be neat to try.' You buy it, and then you get it home and you set it in the cabinet, and it sits there and sits there. And then once or twice a year, you start to clean everything out. And you go, 'I'm not going to eat this … I don't even know how to fix it.' So you turn around and you throw it out."
Jones said Americans buy more things in bulk, whereas Europeans buy smaller amounts of foods, so they can control their loss rates better.
And lifestyle is also a factor. "One of the things we saw in the household, was that people don't think about food in terms of their planning: 'How long is this going to last and when should I use it?'"
Jones said that Americans who work long hours and come home fatigued "don't want to fix meals, so they pull out the frozen food and eat it." Then they may throw out fruits and vegetables they believe are spoiled because they don't understand the process by which they could preserve them for use later.
Commercially, Jones said, "the highest levels of losses percentage-wise are in convenience stores. And the reason for that is the structure in which they provide instant food for people. You can only leave hamburgers and pizzas and things like that out there for so long. And then you eventually have to throw them away."
Jones' study estimated convenience store food losses at 26 percent. Full-service restaurants and supermarkets are much more efficient, he said.
"What happened in the supermarket industry was that a lot of competitors came into the industry and forced them to try to increase their bottom line. And so they had to become more efficient ... and they've done this over the last 15 or 20 years down to the point to where their loss rate is only 1 [percent] to 2 percent, which is incredible when you consider how much food they handle every day."
The Freegans say they find plenty of food that supermarkets simply throw away to clear shelf space for newer products. In a group preparing lunch from the street food that members collected, several people identified themselves as teachers or workers for environmental groups. Alexis Cole is a church music director whose boyfriend went to culinary school.
"I'd say 90 percent of our kitchen is full of stuff from the street. We still buy a few staples like orange juice," she said.
"The majority of my clothes, a lot of amazing hats … shoes … my dresser, a lot of the music that I have, a record player, computer speakers, and a lot of soaps and toiletry products that I have all come from the trash," Cole added.
Still, Krakowski of City Harvest is uncomfortable with the idea of Dumpster diving for food. When told that some Freegans claim never to have gotten sick, Krakowski said, "It's like somebody going through a red light and boasting that they went through a red light. Sometimes you go through a red light and nothing happens and sometimes you go through a red light and something disastrous can happen. It's a risk."
At the University of Arizona, Jones said he is happy for any light that is shed on the problem of food waste. He believes the nation needs a food loss reduction plan. He points to U.S. Agriculture Department statistics indicating that at least 12 percent of American households are "food insecure" at some point during the year, meaning they don't have enough to eat.
"If we were to recover, let's say, 50 percent of the food that was being lost … we would probably triple the amount of food available [for feeding programs] within the United States," Jones said.