Working long hours has a greater negative impact on women than men because it makes them more likely to smoke, drink coffee and eat unhealthy food.
Both sexes consume less alcohol if they spend more time working, researchers said, but toiling extra hours makes women crave unhealthy snacks.
"Women who work long hours eat more high-fat and high-sugar snacks, exercise less, drink more caffeine and, if smokers, smoke more than their male colleagues," said Dr. Daryl O'Connor, a researcher at Britain's Leeds University.
"For men, working longer hours has no negative impact on exercise, caffeine intake or smoking," O'Connor said in a statement released by the Economic and Social Research Council, which funded his study.
O'Connor's team of scientists were studying the impact of stress on eating habits. They looked at what causes stress at home and at work and how people react to it.
The results show that stressful events such as making a presentation, a meeting with the boss or missing a deadline were linked to eating more between-meal snacks and fewer or smaller portions of fruits and vegetables.
"Stress disrupts people's normal eating habits," he said.
The people who were most vulnerable were so-called emotional eaters.
"These individuals have higher levels of vulnerability and tend to turn to food as an escape from self-awareness," O'Connor said.
"When they feel anxious or emotionally aroused or negative about themselves, they try to avoid these negative feelings by turning their attention to food."