Coming home after a long weekend away to a rancid carton of milk or a moldy bunch of berries happens to the best of us. A new study hints at the reason so much of our food gets tossed.

In the study, published online in the journal Resources, Conservation, and Recycling, researchers from The Ohio State University and Louisiana State University analyzed data from 307 participants who took the State of the American Refrigerator survey. Ohio State News reports that they found a sizable disconnect between participants’ expectations of how much food they’d end up eating and how much they actually ate. Survey participants projected a finish rate of 97 percent for meat, 94 percent for vegetables, 84 percent for dairy, and 71 percent for fruit. A week later, they reported the honest outcome: People ate about half the meat, 44 percent of the vegetables, 42 percent of the dairy, and 40 percent of the fruit—they trashed everything else.

According to the survey, people often tossed food because of the dates on the labels, or because they thought it looked or smelled suspicious. But many Americans don’t understand what those ambiguous expiration dates mean in the first place, and therefore opt for a “better safe than sorry” plan of action when the food itself is probably still safe.

Those “expiration” disclaimers could improve soon, though. Congress is currently looking over a proposal to standardize the language so consumers can more clearly interpret it. If Congress passes the proposal, “Use by [date]” will be a nationwide mandate to throw out products after that date, while “Best if used by [date]” will signify that it’s safe to eat or drink as long as you think it seems OK.

Follow-up questions on the survey showed trends in other behaviors that contribute to the likelihood of food waste. People who cleaned out their refrigerators frequently and younger participants wasted food more often, while those who frequently check nutrition labels wasted less. Researchers suggested that people who check nutrition labels are more conscientious about what they buy and less likely to waste it with abandon. It’s possible that they’ve also better educated themselves on which foods are safe to eat after the sell-by dates.

According to the Food and Agriculture Organization of the United Nations, around one-third of the world’s food is lost or wasted—that’s about 1.3 billion tons of food per year.

Feeling a little guilty about your own food waste? Here are eight easy ways to cut back.

[h/t Ohio State News]