Working longer hours may increase obesity risk, a new study suggests. The research, presented at the European Congress on Obesity (ECO 2026) in Istanbul, analysed working patterns and obesity prevalence across 33 OECD countries between 1990 and 2022 and found that nations with longer annual working hours – such as the United States, Mexico and Colombia – also recorded the highest obesity rates.
Lead author Dr Pradeepa Korale-Gedara of the University of Queensland said a poor work-life balance makes it harder to maintain a healthy weight. “When people have a more balanced life, they have a better life,” she said. “They have less stress, they can focus on more nutritious food and engage in more physical activities.”
The study quantified the link: reducing annual working hours by just 1 per cent was associated with a 0.16 per cent drop in obesity rates. The effect was more pronounced in the earlier period of the study (1990–2010), where a 1 per cent reduction in hours corresponded to a 0.17 per cent decrease overall, with a stronger association among men (0.24 per cent) than women (0.17 per cent). In more recent years (2000–2022), the impact appeared weaker, which researchers suggested may be due to policy interventions and increased public health awareness.
How longer hours drive weight gain
The researchers outlined several mechanisms linking extended working hours to obesity. More time spent at a desk means less time for exercise, while long hours often fuel stress-related eating and elevated cortisol levels – both of which are associated with weight gain and fat storage. Workers with little spare time are also more likely to rely on energy-dense convenience foods, a pattern the study authors described in their paper: “These patterns point to potential mechanisms such as reduced time for physical activity, increased work-related stress, and greater reliance on energy-dense convenience foods.”
The study found that average national energy and fat intake did not strongly correlate with obesity rates across countries, suggesting that factors beyond diet – such as working hours, stress and lifestyle – are more significant drivers. For example, Nordic countries maintained relatively low obesity rates despite having higher average calorie and fat consumption. Preliminary analysis indicated that other elements, including sugar consumption, low birth weight and alcohol intake, were influential in OECD countries, while protein intake and smoking had a negative association with obesity.
Where the UK stands
As of 2022, the UK adult obesity rate stood at 26.8 per cent, placing it between the extremes of the 30 OECD countries surveyed. The United States had the highest rate at 41.99 per cent, while Japan recorded the lowest at 5.54 per cent. Several nations including Chile, Mexico and New Zealand had rates exceeding 30 per cent, whereas many Northern and Western European countries remained below 20 per cent. The UK, however, has one of the worst obesity rates in Europe. In England, an estimated 28 per cent of adults were obese in 2022, with a further 36 per cent overweight; the proportion of adults who are overweight or obese has risen from 52.9 per cent in 1993 to 64.3 per cent in 2022.
Childhood obesity is also a significant concern. About 3.8 million children aged five to 19 in the UK have a high BMI – roughly twice the number in France and Italy. In 2022/23, 26.8 per cent of children aged two to 15 in England were overweight or obese. Data for 2023/24 in England showed that 9.6 per cent of reception-aged children (four to five years) were obese and 12.4 per cent overweight, while among Year 6 pupils (10–11 years) the figures were 22.1 per cent and 13.8 per cent respectively. Children in the most deprived areas are roughly twice as likely to be obese as those in the least deprived areas, and severe obesity rates are around four times higher in the poorest neighbourhoods. The cost-of-living crisis has exacerbated health inequalities: the poorest fifth of the UK population need to spend 47 per cent of their disposable income to consume a healthy diet, compared with 11 per cent for the richest fifth.
The UK’s working hours – 1,505 per year in 2022 – place it among the lowest ten OECD countries, well below Colombia’s 2,282 hours or Mexico’s 2,226 hours, but above Germany’s 1,340 hours and the Netherlands’ 1,450 hours. The United States averaged 1,811 hours per year. The study’s findings have added fuel to the debate over a four-day workweek in Britain; campaigners argue it could improve public health by giving people more time for exercise, sleep and home cooking, though the government has said it will not mandate such a change.
Caveats and additional factors
The researchers stressed that the analysis shows an association, not causation, and that income levels and urbanisation also play significant roles. Higher GDP per capita was linked to lower obesity rates – a 1 per cent increase in GDP per capita was associated with a 0.112 per cent reduction in obesity. Living in urban areas had a similar but smaller effect: a 1 per cent increase in urbanisation corresponded to a 0.02 per cent decrease in obesity. However, more than 60 per cent of people with obesity in the UK live in urban areas, and researchers note that “obesogenic environments” – places where unhealthy food is cheap and plentiful and physical activity is difficult – are often found in deprived urban and affluent rural settings.
The study authors concluded: “The findings suggest that the relationship between working hours and obesity is complex and influenced by various socio-economic and cultural factors.” They added: “Higher GDP per capita, greater urbanisation, and higher food prices were negatively associated with adult obesity prevalence, suggesting that improved economic conditions, more supportive urban environments, and higher relative food costs may facilitate healthier dietary choices.”