Bad news: those office freebies could actually be costing you your health.

You may think the occasional free donut or handful of pretzels between meetings is harmless, but new research suggests that might not be the case. A study involving 5,222 employees across the U.S. says that foods typically found in offices are full of calories, sodium, and refined grains, which can derail an otherwise-healthy diet.

The research, headed by Stephen Onufrak, an epidemiologist in the Division of Nutrition, Physical Activity, and Obesity at the Centers for Disease Control and Prevention, suggests that employers could fix this issue by stocking office snack bars with healthier options to better align with the Dietary Guidelines for Americans.

Presenting his findings earlier this week at an annual conference held by the American Society for Nutrition, Onufrak said his study used data from a national household survey issued by the U.S. Department of Agriculture on foods that were purchased or found—in places such as an office kitchen or snack area—by Americans each week.

Onufrak and his researchers looked at what snacks and indulgent treats were purchased from vending machines and corporate cafeterias, or picked up in common areas where free food was available. They also kept an eye out for catering served at meetings or special social events held in workplaces.

More than 25 percent of those surveyed had snacked on food found in the office at least once, and those who snacked ate over 1,300 calories each week. The worst culprit? Free food. Over 70 percent of those calories came from food that didn’t cost anything at all.

“We were kind of surprised that so many of the foods were free,” Onufrak told the Boston Globe. He also wondered if those workers who happened upon free food (such as a dozen donuts near a coffee machine) didn’t consider what kind of caloric impact it would have.

Onufrak says that employers should utilize on-site wellness programs to start discussing nutrition in the workplace—and focus on stocking healthy options within cafeterias, vending machines, and the free snack counter to better serve employees.

At the very least, these new findings could be the reminder you need to skip that cookie the next time you get up to pour yourself a fresh coffee—the “free” treat simply isn't worth it.