Rate of BMI increase among children doubles during pandemic

The rate of BMI increase among children almost doubled during the pandemic, according to researchers, who found that younger kids experienced larger increases than teens and preteens.

The study, published in MMWR, examined trends in BMI increases in Americans aged 2 to 19 years from 2018 to 2020.

“Usually, it's normal for BMI to increase in children,” Aaron Kelly, PhD, co-chair of the Obesity Society’s education committee and co-director of the Center for Pediatric Obesity Medicine at the University of Minnesota Medical School in Minneapolis, told Healio.

“They're growing, their BMIs are going to absolutely increase,” said Kelly, who was not involved in the study. “What they looked at was the rate of increase, and what they showed was that overall, in this age group — 2- to 19-year-olds — the rate of BMI increase doubled during the pandemic.”

The researchers used data from the Ambulatory Electronic Medical Records database to compare trends in BMI among a group of more than 432,000 children and adolescents before and during the pandemic, with dates including January 2018 to February 2020 and March 2020 to November 2020.

Between the prepandemic and pandemic periods, the rate of BMI increase went from 0.052 to 0.100 kg/m² per month, the researchers reported. Children aged 6 to 11 years experienced the largest increase in their rate of BMI change (0.09 kg/m² per month), with a pandemic rate of change that was 2.50 times as high as the prepandemic rate.

Further, most of the children who were categorized as overweight before the pandemic were found to have steeper rises in their BMI compared with peers of normal weight. In both the categories of 3 to 5 and 6 to 11 years, those with BMIs classified as overweight, moderately obese or severely obese at the beginning of the pandemic also gained weight faster than their peers. For those aged 3 to 5 years, for example, children in the normal weight category had an increase in their rate of BMI change of 0.03 kg/m² per month, whereas those with overweight, moderate obesity or severe obesity had increases of 0.06, 0.10 and 0.18 kg/m² per month, respectively.

The gains could cause long-term issues for children and adolescents, Kelly said.

“One thing that we know about excess body weight and excess adiposity is that once you put it on, it's really hard to get it off,” Kelly said. “So, the temptation might be for someone to think here, ‘We shouldn't be too alarmed about the fact that the BMI trajectory increased this steeply during the pandemic, because once we're out on the backside of the pandemic, these kids will just exercise that weight off, or they'll start eating healthier, and the weight will just come right back off, and they'll go back to normal.’ That's probably not what is going to happen here, because most of the literature, scientific literature on adults and children and adolescents tells us that once you put on extra weight, it's exceedingly difficult to get it back off.”

He advised providers to watch their patients’ BMIs, and to refer them to weight management care should they fall into obesity or severe obesity.

“Getting in front of this is going to be really, really important,” Kelly said.

Reference:

Lange SJ, et al. MMWR Morb Mortal Wkly Rep. 2021;doi:10.15585/mmwr.mm7037a3.