By Chris Adams

Not all wasted food is equal.

And not all consumers realize they are wasting food.

Those are two of the primary lessons from JoAnne Berkenkamp, an expert on food waste with the Natural Resources Defense Council, an environmental advocacy organization.

In a session with National Press Foundation fellows, Berkenkamp detailed the often-shocking extent of food waste – from the fact that 40 percent of food goes uneaten (a number that jumps to 52 percent for fruits and vegetables) to the fact that the average American family spends $1,500 on food they throw away each year.

Berkenkamp described some of the reasons for those numbers, including the monstrous portions served in many restaurants to confusion among American shoppers about what the date labels on food mean. Hint: They generally don’t mean the food needs to be pitched; rather, it’s often a sign of peak freshness, even though the food might still be perfectly edible.

One study by retailer Walmart found that its private label goods used more than 40 versions of "use by," "sell by" or "best by"; the chain is working to standardize the labels, hoping to reduce consumer confusion.

Berkenkamp also broke down food waste using a metric of shower minutes. Waste a beer and it’s  the equivalent of four minutes in the shower; waste a pound of beef and it’s the equivalent of six hours in the suds (since raising cattle is water and resource-intense).

Given that three-quarters of Americans think they waste less than the average – a mathematical impossibility – Berkenkamp is somewhat optimistic that the U.S. can get a handle on the issue. But people first need to understand the extent of the problem.

“Can food waste be curtailed?” she asked. “I would say the resounding answer is yes.”