A new national study has revealed a sharp increase in obesity rates in Canada, with the COVID-19 pandemic playing a significant role in accelerating the trend.
Published in the Canadian Medical Association Journal (CMAJ), the research shows that 32.7 per cent of Canadians—roughly 10.6 million adults—were classified as obese in 2023. That’s an eight-point increase since 2009, with the most dramatic uptick occurring during the pandemic years.
“The pandemic had such a profound impact on our daily lives, especially our eating habits and access to healthy food,” said lead author Laura Anderson, a professor of health research and methods at McMaster University.
Obesity, defined by a body mass index (BMI) of 30 or more, is linked to serious health risks including stroke, Type 2 diabetes, and certain cancers. The study examined data from over 746,000 Canadians aged 18 and older between 2009 and 2023. Although BMI has its limitations—failing to account for gender, ethnicity, or actual body composition—it remains a standard for tracking trends in population health.
Anderson noted that prior to the pandemic, obesity rates were rising by about 0.5 percentage points per year. But during COVID-19, that rate doubled. “The pandemic intensified existing trends,” she said, though the study did not explore precise causes.
Dr. Sean Wharton, a southwestern Ontario internal medicine specialist and obesity expert unaffiliated with the study, believes mental health played a key role. “Isolation, depression, and the stress of uncertainty took a toll,” he said. “People living with depression often gained weight during that period, and once it’s gained, it’s difficult to reverse.”
The data also revealed specific demographic shifts. The highest increase was seen among young adults aged 18 to 39, and women were more likely to become severely obese—defined as a BMI of 40 or more. Anderson suggested that increased caregiving responsibilities and stress may have disproportionately affected women during lockdowns.
Angela Martin, a nurse in Toronto, lived through that reality. In 2020, she was juggling her job at a family clinic and navigating a separation from her partner. “Looking back, I was so not fine,” she said. “You couldn’t go to the gym, so I stayed home and cooked—it was the only thing I had control over.”
While the overall rise in obesity is concerning, researchers are especially worried about the spike in severe obesity. In 2009, 2.4 per cent of Canadians were severely obese; by 2023, that number had doubled to nearly five per cent. Wharton warns this will likely lead to more chronic conditions, such as osteoarthritis, heart disease, and Type 2 diabetes.
Interestingly, while half of those classified as obese reported no chronic health conditions, five to ten per cent had three or more, including life-altering illnesses like stroke and cancer.
One potential game-changer may be the emergence of new weight-loss medications like Wegovy. Approved by Health Canada last year, such drugs could begin to shift future obesity trends, though they were not widely available during the period covered by the study.
For now, researchers say the data offers a wake-up call. The long-term effects of pandemic living are still unfolding—and they’re showing up in our health.