It’s pretty apparent that what you put in your mouth has a significant impact on how fit you are. Now, new research shows that what passes through your ears might play a role as well.

Working out of the University of Oxford and the University of Leicester, researchers tied living in an area where traffic noise was prevalent to an increase in body mass index (BMI) and waist circumference—two key measurements in determining obesity.

“While modest, the data revealed an association between those living in high traffic-noise areas and obesity, at around a two percent increase in obesity prevalence for every 10 decibels of added noise,” said lead author Dr. Samuel Yutong Cai, a senior epidemiologist at the University of Oxford. “The association persisted even when we accounted for a wide range of lifestyle factors, such as smoking, alcohol use, physical activity, and diet, as well as when taking into account the socio-economic status of both individuals and the overall area. Air pollution was also accounted for, especially those related to traffic.”

Banking on the Biobank

To reach their conclusions, the researchers examined data from 500,000 people who had their health information contained in biobanks in Norway, the UK, and the Netherlands. 

The researchers believe the relationship between noise and weight gain has to do with the stress the constant sound of traffic can create in nearby residents, as well as the sleep it can steal. Both stress and lack of sleep have been tied to weight gain in other studies.

“It is well-known that unwanted noise can affect quality of life and disturb sleep,” says co-author Professor Anna Hansell, Director of the University of Leicester’s Centre for Environmental Health and Sustainability. “Recent studies have raised concerns that it also may influence general health, with some studies suggesting links to heart attacks and diabetes. Road traffic noise may increase stress levels, which can result in putting on weight, especially around the waist.”

The research has been published in the peer-reviewed journal, Environmental Research.