A new study has found that more people weighed in as obese during the first year of the COVID-19 pandemic than the previous year.

The evidence was presented from a large, nationally representative survey that showed this trend and helped researchers to explain behaviour changes that led to widespread weight gain in 2020. The findings of the study were published in the American Journal Of Preventive Medicine.

"Previous studies present evidence that intra-pandemic changes in risky dietary and other health-related behaviours are likely to contribute to the rapid rise in body weight during this period.

Adults who reported weight gain also reported more frequent snacking and alcohol intake; increased eating in response to sight, smell and stress and decreased physical activity," explained lead investigator, Brandon J. Restrepo, PhD, US Department of Agriculture, Economic Research Service, Food Economics Division--Diet, Safety and Health Economics Branch, Washington DC, USA.

Adult obesity was elevated and trending upward prior to the COVID-19 pandemic. The analysis of the BRFSS data employed linear regression models that control for age, sex. race/ethnicity, education, household income, marital status, number of children, survey year indicators and state of residence indicators.

According to the analysis of more than 3.5 million adults in the US (aged 20 or older) from the 2011-2020 BRFSS, obesity was 3 per cent more prevalent during the year beginning March 2020, compared with 2019 to pre-pandemic 2020 period.

The study also found statistically significant changes in four obesity-related risk factors during the COVID-19 pandemic:

• Exercise participation
• Sleep duration
• Alcohol consumption
• Cigarette smoking.

While exercise participation and sleep duration were higher by 4.4 per cent and 1.5 per cent, respectively, the number of days in which alcohol was consumed was 2.7 per cent higher and cigarette smoking prevalence was lower by 4 per cent.

The overall increases in exercise and sleep were not sufficient to offset the impact of other behaviours, resulting in an average 0.6 per cent rise in body mass index during the COVID-19 pandemic. Although smoking cessation is a healthy step, it is known to cause some weight gain.

"Our results, which are broadly consistent with what prior studies have found using smaller and less representative samples, contribute additional insights that can serve to inform policymakers about the state of the US adult obesity epidemic and obesity-related risk factors," noted Dr Restrepo.

"Because obesity affects some adults more than others, it would be helpful to further explore the changes in the rates of adult obesity by demographic subgroup and socioeconomic status," he added.