ISTANBUL — Research presented at the European Congress on Obesity in Istanbul compared working patterns and obesity prevalence across 33 OECD countries between 1990 and 2022, finding that reducing annual working hours by 1% was associated with a 0.16% decrease in obesity rates. The study reported that the United States, Mexico and Colombia, which have longer annual working hours, also had higher obesity rates.

The authors concluded that a lack of time for exercise and work-related stress could explain why those who work the longest hours are more likely to gain weight. The researchers cautioned that the study does not prove causation and that the income levels of different countries could also be a factor.

Dr Pradeepa Korale-Gedara, a researcher at the University of Queensland, said: "When people have a more balanced life, they have a better life. They have less stress, they can focus on more nutritious food and engage in more physical activities."

Dr Rita Fontinha, a psychologist at the University of Reading, linked long hours to poorer diets. "If you work two jobs or long hours, you simply do not have the energy to cook and it becomes easier to just buy something packaged or processed," she said. "A four-day week or different forms of working-time reduction could be associated with better choices in terms of food, exercise and sleep to contribute to healthier societies." Fontinha added.

James Reeves, campaign manager at the 4 Day Week Foundation, called for wider adoption of shorter working weeks. "A four-day week on full pay could slash Britain's obesity levels by giving millions the time they need to ditch bad habits and make healthier choices," he said. "It's essential that local and national governments seriously consider the role that a shorter working week can play in improving the health of our communities. The nine-to-five, five-day working week is 100 years old and we're long overdue an update," Reeves said.

About 200 companies have adopted a four-day week for their employees, and South Cambridgeshire district council has introduced a four-day week for all staff. Office for National Statistics data shows that more than 200,000 workers have switched to a four-day week since the Covid-19 pandemic.

A government statement ruled out a mandated change. "This government will not mandate a four-day work week for five days' pay. But through the Employment Rights Act, we're making it easier for flexible working requests to be accepted," the statement said.