Overtime, Overtired, and Overweight: Workplace Can Affect Weight Gain

Just as in many other parts of the world, the prevalence of obesity has steadily increased in Finland. Researchers there have turned their attention to the workplace as another factor that may be contributing to this trend.

Dr. Tea Lallukka and colleagues at the University of Helsinki report that work fatigue and working overtime are the greatest risk factors for weight gain (Int J Obesity 2005; 29:909). They concluded this from responses on questionnaires mailed to 40- to 60-year-old women (7093) and men (1799) employed by the City of Helsinki during 2000-2002. The subjects are participants in the ongoing Helsinki Health Study (for more about this study, see www.kttl.helsinki.fi/hhs).

The questionnaires

The questionnaire included a work fatigue index, a mental stress index, and an evaluation of conflicts between work and home, and also asked about weight changes during the previous 12 months. The variables describing job demands and control of the job environment were based on Karasek’s 1979 model of job strain. (Dr. Karasek is the author of the Job Content Questionnaire, an instrument used in measuring stress in Europe, Japan, and the U.S.) The work fatigue index from the questionnaire included six items on stress and exhaustion at work, such as “I feel totally worn out after a day at work,” and “I worry about my work even when I’m off duty.” If the respondent answered 4 of the 6 items in the affirmative, this was counted as high work fatigue. Working overtime was defined as working more than 40 hours per week, and mental stress at work was determined by how mentally straining the respondents considered their work to be. If they reported it was very hard, this was categorized as “high.”

To quantify stress between work and home life, respondents were asked how satisfied they were with combining paid employment and family life. Social support was divided into three categories of low, medium, and high, based on positive responses to questions about support at home and at work.

Weight gain followed work stress and fatigue

During the previous year, 24% of the women and 19% of the men had gained weight. Differences in the prevalence of past weight gain by working conditions were minor. However, a statistically significant difference between the extreme categories was often found, especially among women. More than 30% of women with high work fatigue or those dissatisfied with their work-home situation had gained weight during the past year. Working overtime was also associated with weight gain in women. Women who were not happy with their work-home situation were also more likely to have gained weight than were their satisfied counterparts. Among men, weight gain was most common among those who reported work fatigue (26%), very high job demands (24%), or those with high mental strain at work (24%).

Why did the workers gain weight?

One of the explanations for the association between working overtime and weight gain could be as simple as an increased intake of snacks and fast food. These foods are usually high in energy and fat and workers might eat them instead of regular meals because of lack of time. Those reporting work fatigue might also be too tired to consider or plan a healthy diet and to prepare healthy meals instead of replacing them with fast foods. In addition, this same group might be too tired from work to exercise, and thereby could gain

even more weight because of low activity. The authors did not find any associations between job demands, a sense of control on the job, and weight gain among women. Dr. Lallukka and her colleagues suggest that because obesity is such a serious health issue, worksite health promotions by public health groups should focus on ways to counteract unhealthy conditions at work.