You and your coworkers work late on a project and your boss orders in pizza for the group.

You gather ‘round the conference table for a meeting and the office brings in a giant platter of sandwiches, chips and treats.

Your officemate celebrates a big birthday and everyone digs into a slice of frosting-laden sheet-cake, standing around with paper plates, making awkward small talk before they can get back to their desks without looking rude.

Everyone loves free food at the office. Who’s going to say no to those doughnuts someone has left by the coffee machine? But it turns out those extra calories – not to mention the food you buy in the work cafeteria or the snack from the vending machine — really add up.

According to a new national study, in which 5,222 U.S. employees recounted what they had eaten at work during a span of seven days, working adults consume nearly 1,300 calories from food and beverages obtained at work – either provided for free or purchased from the workplace cafeteria or vending machine — each week. That’s more than half the recommended daily intake of calories for the average adult, albeit consumed over the course of a week.

"With employees spending eight hours a day on average at their place of employment, a lot of people may not be aware of all of the calories they get from work, especially from foods they get for free," lead author Stephen Onufrak, an epidemiologist in the Centers for Disease Control and Prevention’s Division of Nutrition, Physical Activity and Obesity, told ABC News.

The study, which has not yet been published but was recently presented at the American Society for Nutrition's annual meeting in Boston, found that about 22 percent of working adults obtained food at work during the week of the study and that they were far more likely to get the food for free than purchase it. In fact, about 71 percent of the calories consumed at work were from free food, according to the study.

Most of the foods consumed were not terribly healthy, it may not surprise you to learn. We’re not talking fresh fruits and veggies here. “The leading food types obtained include foods typically high in solid fat, added sugars, or sodium such \as pizza, soft drinks, cookies/brownies, cakes and pies, and candy,” the authors wrote, recommending workplace wellness initiatives to improve food options.

"Since we found that a lot of the foods obtained by employees were free, employers may also want to consider healthy meeting policies to encourage healthy food options at meetings and social events," Onufrak said in a press release announcing the results of the study.

And, hey, workers of the world, it wouldn’t hurt to turn down those free doughnuts once in a while, either. Don’t say you weren’t warned.

Photo: iStock