Last year, Mom’s Organic Market founder and chief executive Scott Nash did something many of us are afraid to do: He ate a cup of yogurt months after its expiration date. Then tortillas a year past their expiration date. “I mean, I ate heavy cream I think 10 weeks past date,” Nash said, “and then meat sometimes a good month past its date. It didn’t smell bad. Rinse it off, good to go.” It was all part of his year-long experiment to test the limits of food that had passed its expiration date. In the video above, we interviewed Nash about his experiment and examined where expiration dates come from and what they really mean.

It turns out that the dates on our food labels do not have much to do with food safety. In many cases, expiration dates do not indicate when the food stops being safe to eat — rather, they tell you when the manufacturer thinks that product will stop looking and tasting its best. Some foods, such as deli meats, unpasteurized milk and cheese, and prepared foods such as potato salad that you do not reheat, probably should be tossed after their use-by dates for safety reasons.

Tossing out a perfectly edible cup of yogurt every once in a while does not seem that bad. But it adds up. According to a survey by the Harvard Law School Food Law and Policy Clinic, the Johns Hopkins Center for a Livable Future, and the National Consumers League, 84 percent of consumers at least occasionally throw out food because it is close to or past its package date, and over one third (37 percent) say they always or usually do so. That food waste in landfills generates carbon dioxide and methane, a greenhouse gas 28 to 36 times more effective at trapping heat in the atmosphere than carbon dioxide. And you are not just wasting calories and money. You are wasting all the resources that went into growing, packaging and transporting that food.