So much for working our butts off.

More than half of American employees think they’re overweight, and most blame their jobs for that.

A CareerBuilder survey of more than 3,400 workers out Thursday – smack in the middle of Global Employee Health and Fitness Month – reveals that 45% of workers say they’ve gained weight at their current job.

And it’s more than just one or two extra pounds from that break room bagel. One in four said they packed on 10 pounds in their current position, and one in 10 gained more than 20 pounds.

Amanda Ponzar, chief marketing officer at Community Health Charities, told Moneyish she’s put on between 5 to 10 pounds in the nine months since taking this job. “I sit at my desk working furiously, or I’m in meetings all day, plus I have been enjoying all the treats people bring in, like doughnuts, cookies,” she said. “Plus office events, lunches out with clients, all the sugary caffeinated beverages to stay motivated … it’s all definitely caused me to gain more weight.”

She’s not alone. More than half (51%) of all surveyed workers blamed being stuck behind a desk all day for tipping the scales against them, and they’ve got a point. Research shows that the longer we sit, the higher the risk of obesity, diabetes, heart disease and cancer.

Finance workers in the CareerBuilder survey were more likely to point the finger, with 57% of workers in that industry believing their job caused their weight gain, followed by those in health care (50%), transportation (50%), sales (50%) and  IT (44%).

Other polled employees griped that exercise doesn’t fit in their schedules; 45% said they were too wiped from work to workout, and 38% said they had no time to squeeze in sweat sessions before or after their shifts. As a result, 41% admitted they don’t work out at all, let alone get the 150 minutes of moderate-intensity physical activity (like brisk walking) a week recommended by health experts.

Josh Haber, 24, who works at the housekeeping and lawn service start-up All Set, feels their pain. “Start-up life means long hours, and less time to exercise,” Haber, who gained about 18 pounds, told Moneyish. “Also, the more stressful work is, the more individuals can be exhausted once they actually finish work, diminishing the drive to exercise afterward.”

Some workers added that their workload wreaks havoc on their eating habits, with 38% of them stress eating, 24% turning to takeout regularly and 19% skipping meals because of time constraints – which leads to 12% of workers making a meal from vending machine crap. Another 78% admit to snacking on the job.

Employers should weigh the issue carefully. Being overweight or obese was linked to higher worker’s compensation costs. And obese employees are more likely to take sick leave and are more easily fatigued and require more rest time.

“Employee health is an incredibly important issue for employers, as suboptimal health can negatively impact workplace productivity, efficiency and morale,” said Rosemary Haefner, chief human resources officer at CareerBuilder. “Providing employees the tools they need to get and stay healthy, then encouraging their workers to use these benefits, is a surefire way to maximize your talent and encourage employee loyalty.”