Also, some jobs are riskier than others.
The survey of US workers found that 41 percent of people have gained weight in their current job, News.com.au reported.
The workers most likely to report weight gain were administrative assistants (69 percent), followed by engineers (56 percent), teachers (51 percent), nurses and physician's assistants (51 percent), IT managers/network administrators (51 percent), and lawyers and judges (48 percent).
The CareerBuilder survey of more than 3600 full-time workers found that the biggest blame for work weight gain was sitting at a desk for most of the day, with 56 percent saying this was a cause.
The second most common reason was eating because of stress (35 percent), followed by eating out regularly (26 percent) and the temptation of the office lolly jar (17 percent).
Nutritionist Susie Burrell says too many people use food as a reward for being at work.
"It's often a learnt response from when we were young, we were soothed by food, we'd cry and we'd get a lolly," she said.