Obesity rates in Canada surged during the pandemic, study finds

The percentage of Canadians living with obesity increased sharply during the COVID-19 pandemic, rising at nearly double the rate of the years before, according to a new study published in the Canadian Medical Association Journal.

The study analyzed data from 746,250 adults surveyed through the Canadian Community Health Surveys between 2009 and 2023. Researchers found that the number of adults with obesity, defined as a body mass index (BMI) of 30 or higher or over 27.5 for people of Asian descent, increased from 24.95 per cent in 2009 to 32.69 per cent in 2023. 

That's an increase of almost eight percentage points, representing about 10.6 million people.

"The rate of increase doubled," said Arthur Sweetman, Ontario Research Chair in Health Human Resources at McMaster University and co-author of the study. "You can think of it like there was a big acceleration and the speed doubled during COVID, and if we stay at that much higher speed, then that's a very serious issue."

Sweetman said the study used self-reported height and weight data, so it can't determine exact causes, but the timing aligns with changes in daily life.

"People were clearly less active during COVID," he said. "They weren't commuting to work, they weren't doing their normal daily activities, and they were spending more time at home, which meant perhaps that they were eating differently than they had eaten before."

He also noted the broader impacts of stress. "It was also a very stressful time for a lot of people, and stress obviously has a relationship."

Joanne Alano, a registered dietitian with the St. Albert and Sturgeon Primary Care Network, said stress and isolation may have had an impact; however, the exact causes are unknown. 

"There's so many different variables. Part of it is people were just locked inside. There were less things to do with restaurants, less social things or third spaces that were available because they were closed," she said.

Alano said people respond to stress differently, and some may have turned to emotional eating. She also pointed to a rise in alcohol use during lockdowns and limited access to gyms and recreational sports as contributing factors.

Young adults and women experienced some of the most significant increases in obesity, according to the study. While obesity rates have long been higher among older age groups and men, the pandemic period saw faster growth in groups that previously had lower rates.

"The people that were affected more are the people who traditionally have lower rates of obesity," Sweetman said. "Which were younger people and women in particular."

The study also showed that more severe forms of obesity rose at a faster rate than milder cases, suggesting a shift toward higher health risks. Obesity is linked to numerous chronic conditions, including type 2 diabetes, high blood pressure and heart disease.

"There is research to show that with more of these ultra-processed foods or more of the fat, sugar, and salt, it can increase risk of, yes, obesity, but also type two diabetes, high blood pressure, high cholesterol," Alano said. "Just general overall, not feeling great, like fatigue, that kind of thing."

Alano said she doesn't want to demonize ultra-processed foods, as they do have a purpose, and they are what some families can afford. She added that if you are looking for healthier food, shop along the outside perimeter of the grocery store. 

While BMI is widely used in health research, Alano cautioned against taking it as an exact measurement.

"It's not accurate, and it may not be reflective of all populations," she said. "It should be taken with a big grain of salt."

Sweetman said it's still unknown whether the spike in obesity rates will level off in the coming years or whether the rate of increase will remain elevated. He explained that further research will be needed to determine the effects. 

"We don't know if this is a temporary thing," Sweetman said. "We're worried about the percentage of people who have obesity, and we're worried about the rate of increase in the future."