Dr Pradeepa Korale-Gedara from the University of Queensland, who led the study, said that lack of time for exercise and work-related stress may explain the link. She noted that when people have a more balanced life, they experience less stress and can focus on nutritious food and physical activities. Workplace stress increases the hormone cortisol, causing the body to store more fat, she added.
When stressed, the body releases cortisol, which triggers glucose release from the liver into the bloodstream. Modern lifestyles mean stressful situations often occur while sedentary, so glucose is not used up and may be converted into fat. Increasingly, people work in jobs where they are unable to burn energy, Dr Korale-Gedara noted.
Manual jobs are more mechanised now in developed nations, meaning workers on long hours find it impossible to burn enough fat while relying more on convenience food. The study found that the US and Latin American countries tend to work longer hours and have higher obesity rates. However, Northern European countries consume more energy and fat on average than Latin American countries, yet have lower obesity rates.
The study does not prove causation; income levels of different countries may also be a factor, the researchers acknowledged. In the UK, where three in ten Brits are obese, the findings have implications for policy. Dr Korale-Gedara suggested that a four-day week, representing a 20% reduction in working hours, would be linked to around half a million fewer people being obese in the UK.
She mentioned that there is a debate in Australia about four-day weeks, with research looking at productivity gains, but now people are considering it from a different perspective, and she thinks it is something that can be considered.