"Over the last few decades, there has been an increase in the number of Americans engaging in precarious work -- we see this with the rise of the 'gig' economy or the number of people working for ride-share companies, for example. With millions of Americans now engaging in precarious work, we need to pay closer attention to the health impacts of type of employment," study author Vanessa Oddo, assistant professor of kinesiology and nutrition at the UIC College of Applied Health Sciences, said.

To understand the impact of precarious work on BMI, the researchers analysed 20 years of data from the National Longitudinal Survey of Youth adult cohort (1996-2016). The average age of the participants was 44.

They looked at seven precarious employment dimensions -- material rewards, working time arrangements, employment stability and collective organization, for example -- and identified 13 self-reported survey indicators of precarious employment. Computational and statistical models were used to compare these indicators with BMI, a rough indicator of obesity.

Indicators of precarious employment were highest among Latino and Black women with lower education. A 1-point increase in precarious employment was associated with a 2.18-point increase in BMI.

The findings are reported in Obesity.

The researchers say that "these modest changes in BMI may have important implications at the population level, given that small changes in weight affect chronic disease risk.

"Policies and workplace interventions to improve employment quality warrant consideration to protect American workers and mitigate the growing burden of obesity-related chronic diseases in the United States," the authors write.