While some areas of food labeling are strictly regulated, food dating seems rather arbitrary. What is the real difference between "sell by", "best by" and "use by"? And what happens if you eat food after this date? I did some research to find out. 

Each food item has a unique journey to your kitchen table, and this determines the labeling it carries. Let's take milk as an example: it is collected on a dairy farm and is then sent to a dairy processing plant. There the milk is pasteurized and packaged before being delivered to grocery stores, where it may sit a while before purchase. In this case, companies use food dating to communicate both to store owners when a carton of milk should be taken off the shelf and to customers when the milk should no longer be consumed.

"Best by" dates are not expiration dates, however. They merely mark the last day before food quality declines. In fact, experts claim that milk may be good for up to a week after its printed date (always use visual cues and common sense before indulging, however). So if "best by" dates aren't regulated and they don't indicate expiration, why do companies print them?

Food dating came into the picture in the 1970s when consumers were producing less of their own food but still wanting information about how it was made. Food companies realized that a spoiled food product may turn consumers away from a certain store or food brand, and so they chose date ranges to keep food in peak condition. Since then, food dating has been streamlined:

"Best by" indicates when a product will be of best flavor or quality. 

"Sell by" is used by manufacturers to ensure proper turnover throughout the journey of the food product. This helps the food retain a long shelf life even after purchase.

"Use by" marks the last date recommended for the use of the product. This is often printed on meat, poultry or egg labels and should be taken seriously.

What Happens if You Eat Food After the Date?

As previously mentioned, sometimes eating food after the "best by" date simply means a decline in quality. Yogurt, for example, can be eaten 14 to 24 days after the printed date, but it will become increasingly sour during that time. 

Other foods, however, might make you sick, and the symptoms can range from a stomach ache to full-on food poisoning. Experts say that chicken is one of the worst offenders: listeria was found when the poultry was stored in the fridge for 2 weeks past its "use by" date.

So how can you really be sure that food is okay to eat after the expiration date? Remember the difference between "best by" and "use by": milk, cheese, and bread can all last for varying time after their "best by" date when left unopened and stored properly. However, it is not recommended to ignore the "use by" date of meat, poultry or eggs.

Food Dating Regulation

The Food and Drug Administration (FDA) does not have formal regulation for food dating. Last year, however, the Food Marketing Institute and the Grocery Manufacturers Association came together to create their own rules. While they aren't backed by the government, these organizations carry enough clout that food companies have taken notice. "Best by" and "sell by" indicate quality while "use by" indicates safety. 

After researching, it's clear that there is a benefit to multiple terms for food dating. "Use by" is more serious whereas "best by" has to do with flavor. But despite these guidelines, remember to always use common sense when trying something from the back of the fridge.