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Studies report children gained weight during the pandemic

Two US studies have reported that children gained excess weight during the COVID-19 pandemic and the researchers urged policy-makers to develop diet and activity interventions to help children achieve and maintain a healthy weigh.

In the first study, ‘Changes in Body Mass Index Among Children and Adolescents During the COVID-19 Pandemic’, published in JAMA, researchers from Kaiser Permanente who studied nearly 200,000 children reported that gained excess weight during the COVID-19 pandemic, especially those between 5 and 11 years old.

"When we compared the weight gain among children from 2019 to 2020, we found that there was more weight gained during the pandemic for youths of all ages," said the senior author, Dr Corinna Koebnick of the Kaiser Permanente Southern California Department of Research & Evaluation. "And, this weight gain fell disproportionally on the youngest children. On average, 5- to-11-year-olds gained 5 extra pounds, while 16- to-17-year-olds gained 2 extra pounds. The result was an almost 9% increase in the youngest children falling into the categories of being overweight and obese. As children go back to school it will be important to focus on health and physical activity to help children not carry unwanted extra weight into adulthood."

To determine if children picked up extra weight during the pandemic, researchers analysed the electronic health records of 191,509 members of Kaiser Permanente in Southern California who were age 5 to 17 from March 2019 to January 2021.

They found that children aged 5 to 11 years gained 5.07 pounds more during COVID-19 than during the same time period before COVID-19, while youth age 12 to 15 years and 16 to 17 years gained an excess of 5.1 pounds and 2.26 pounds over the prior year, respectively.

Among 5-to-11-year-olds, this weight gain resulted in almost 9% more children becoming overweight or had obesity compared to 5% in youth ages 12 to 15 years and 3% in youth ages 16 to 17 years. Most of the increase among youths 5-11 and 12-15 years old was due to an increase in obesity.

"We need to immediately begin to invest in monitoring the worsening obesity epidemic and develop diet and activity interventions to help children achieve and maintain a healthy weight," Dr. Koebnick said.

In the second study, ‘COVID-19 pandemic accelerates children's weight gain, BMI’, published in the American Journal of Preventive Medicine, led by researchers at the University of South Carolina's Department of Exercise Science, found increases in body mass index (BMI) scores among school-age children. The increase is likely a result of school closures, food insecurity and fewer outdoor activity opportunities.

"The COVID-19 pandemic has introduced a variety of significant disruptions to individuals' lifestyles that could negatively impact children's health behaviours and weight status," explained Dr Glenn Weaver, assistant professor of exercise science and lead author on the study.

The researchers outline several factors that have likely contributed to this trend: stay-at-home orders that reduce opportunities for outdoor play while increasing screen time; rising levels of food insecurity (as much as 35 percent) coupled with a growing reliance on shelf-stable, ultra-processed foods; and a lack of structured days (at school/summer camp). These factors have been previously linked to obesity risk in children.

Weaver and his colleagues at the Arnold Childhood Obesity Initiative research group are particularly interested in how the presence or absence of a structured day affects children's health. Through their National Institutes of Health-funded studies, they have found that the structured days offered at school and summer programming offer a greater number of opportunities to engage in healthy behaviours.

The preplanned, compulsory, adult-supervised activities provided by schools positively impact children's sleep, diet, physical activity and screen time behaviours - all of which affect children's weight. For example, variable/later sleep schedules have been linked to obesity. Further, a lack of access to school meals exacerbates food insecurity and children's dependence on processed foods. Additional research has shown that children's BMI gain accelerates during summer vacation from school due to the same factors.

The team examined the BMI changes in more than 1,700 elementary school children across three schools in the same district. They found an acceleration in BMI changes that was ten times greater during the COVID-19 pandemic than in previous years, with the increase seen across children of different racial groups, grade levels and sexes. The authors note that the accelerated changes in BMI translate to an increased risk of becoming overweight or obese.

"Although there are a variety of reasons that children's BMI gain increased during the COVID-19 pandemic, the closure of the school buildings was likely a major driver of these increases," added Weaver, who notes that preliminary reports indicate that during the pandemic, children have become more sedentary and less physically active, eat more unhealthy and fewer healthy foods, experience later and more variable sleep schedules, and engage in more screen time. "The impact of the COVID-19 pandemic on children's BMI was not unexpected, but the magnitude of the acceleration in change is alarming and supports the urgent need for public health interventions to address overweight and obesity, especially in children from minority and low-income families."

Further information

Changes in Body Mass Index Among Children and Adolescents During the COVID-19 Pandemic, JAMA - to access this paper, please click here

COVID-19 Leads to Accelerated Increases in Children's BMI z-Score Gain: An Interrupted Time-Series Study, American Journal of Preventive Medicine - to access this paper, please click here


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