What does a food expiration date mean? I contemplated this several weeks ago, when I had nothing to make for dinner except eggs that were four weeks past the "sell-by" date on the carton. I'd heard that eggs can be eaten up to five weeks after the "sell-by" date, so I took my chances and made an egg sandwich. It didn't taste fresh or good at all, but I was relieved not to contract some horrible illness from rotten eggs.

I could have easily thrown the eggs away and contributed to the $165 billion worth of food that goes to waste every year. But as Business Insider pointed out in a new piece, many expiration dates are meaningless and end up scaring people into tossing out perfectly edible food. The National Resource Defense Council (NRDC) says that expiration dates are merely "suggestions by the manufacturer for when the food is at its peak quality, not when it is unsafe to eat."

The NRDC reiterates that expiration dates cause many Americans to squander billions of dollars in food every year, adding that forty percent of the food produced annually never gets consumed. The organization, which aims to protect the earth, recommends a labeling system that better explains to consumers how long their food will last beyond the "sell-by" date.

The confusion with labels

When you see a "use by" date on food or medicine, that means the listed date is the last day the item will be top quality. This doesn't necessarily mean it will rot (or in the case of medicine, no longer work) after the "use by" date. If it's medicine, it will be less effective, and if it's food, it might not be as fresh.

You do, however, have to be careful about foods after they've reached a certain point past the expiration date. Mold and smell are good indicators that something is no longer safe to consume.

"If foods are mishandled, foodborne bacteria can grow, and if pathogens are present, cause foodborne illness — before or after the date on the package," the U.S. Department of Agriculture writes on its site.

According to the U.S.D.A., "sell-by" or "expiration" (EXP) dates are not federal requirements on packaging, but states may have different requirements. The U.S.D.A. reports that some state egg laws forbid "sell-by" dates to appear on cartons. That's why the U.S.D.A. says the eggs are fine to eat 3 to 5 weeks after purchase:

U.S.D.A. - usda.gov

U.S.D.A. - usda.gov

Comedian John Oliver noted the absurdity over food waste last month, acknowledging that he understands why food producers might intentionally confuse consumers with expiration dates and mislabeling in order to get more business:

“If I were a food manufacturer, I would make those dates as tight as possible to convince people to buy a new one of my products," he said.

So, while your eggs might not be as tasty and fresh as they were prior to the carton "sell-by" date, they're not going to go bad on you for a few weeks.