Publisher Health

Childhood obesity has increased significantly in the United States during the past four decades. In 1980, about 5 percent of the country’s children between 2 and 19 were experiencing obesity, according to the C.D.C.; as of 2018, more than 19 percent were — and an additional 16 percent were considered overweight. Because children are far more likely to gain an unhealthful amount of weight while out of school over the summer, experts were worried last spring when in-person schooling was suspended indefinitely because of the pandemic. They feared extended closures might “exacerbate the epidemic of childhood obesity and increase disparities in obesity risk,” as researchers from the Mailman School of Public Health at Columbia University and colleagues put it in a paper in the journal Obesity in June 2020. That, in turn, would mean more children living with related conditions such as Type 2 diabetes, hypertension and fatty-liver disease.

Those concerns were warranted, according to a May study in Pediatrics. Based on measurements of body mass index taken for more than 500,000 children between the ages of 2 and 17 during visits to the Children’s Hospital of Philadelphia Care Network, researchers found that, on average, between January 2019 and December 2020 the prevalence of obesity increased by almost 2 percentage points overall, from 13.7 percent to 15.4 percent. (In the most recent years for which national data is available, the increase has been 1 percentage point or less.) Black and Latino children, as well as those from families with lower incomes, displayed sharper increases than children from other groups did. Such gains early in life make it more likely that children will have higher B.M.I.s when they grow up. (Obesity already affects more than 40 percent of American adults.) “This isn’t just baby fat that’s going to go away,” says Brian Jenssen, the study’s lead author and a pediatrician at Children’s. “That’s why I think this is so alarming.”

Analyzing what children do differently during the school year compared with the summer months has led researchers to single out factors that can contribute to unhealthful weight gain. Schools often serve more nutritionally balanced meals than children get at home. At school, students eat on a regular schedule and find it difficult to snack throughout the day. Schools also offer opportunities for physical activity, which are more limited for children who live in neighborhoods that lack outdoor amenities or are unsafe. “In downtown Baltimore, where our murder rate is so high, you’re not letting your kid go out and play in a park,” says Maureen Black, a psychologist and professor of pediatrics, epidemiology and public health at the University of Maryland School of Medicine. That tends to mean that children spend more time in front of screens, sedentary and often snacking. A lack of school structure can also contribute to altered sleep-wake patterns, which have been associated with unhealthful weight gain.

But while it has been possible to identify ways that schools can help prevent B.M.I. increases, it has been harder to figure out how to replicate those conditions when classes aren’t in session. For example, only about three million of the 22 million children who receive free or reduced-price lunch during the school year get the meals they’re eligible for over the summer. Those meals are typically more balanced nutritionally than the cheaper, calorie-dense fare that families resort to when food is scarce. Inconsistent access to food can also cause physiological changes that heighten the risk of obesity; school closures and job losses during the pandemic greatly increased the number of children without a stable source of nutrition. In June 2020, more than 27 percent of U.S. households with children were experiencing food insecurity; in about two-thirds of them, there was evidence that the children, in addition to adults, weren’t getting enough to eat — more than 5.5 times the number who reported those circumstances in all of 2018, according to the Brookings Institution. In addition, many families with sufficient resources were buying more ultraprocessed, shelf-stable foods for comfort and in preparation for possible lockdowns or supply shortages.

The crisis did force federal, state and local agencies to improvise novel ways of getting more balanced meals to children outside a school setting. To limit infection risk and reach more students, for instance, the U.S.D.A. offered waivers to what is known as its “congregant feeding” requirement that children eat on-site. This allowed caregivers to pick up multiple days’ worth of meals; some districts converted school buses running along their regular routes into a food-delivery service. The agency also made all children eligible for free lunch through September 2021, eliminating the paperwork required to qualify and the stigma that often comes with it, says Eliza Kinsey, a professor of epidemiology at the Mailman School of Public Health and an author of the Obesity paper. Such “program flexibility,” she points out, “could be applied in other, non-Covid contexts,” such as during the summer or for other disruptions like hurricane and wildfire closures.

It stands to reason that broadening access to nutritious foods would help prevent childhood obesity going forward. But schools also play a central role in the collection of nationally representative health data for children, a process that has been disrupted by school closures. We don’t know yet if the nearly 2 percentage point increase observed in the Philadelphia area will be similar across the country — or how much expanded feeding programs have mitigated the many and varied risk factors for obesity imposed by the pandemic.

Still, other pediatric hospital networks have reported worrying increases not just in obesity but also in the conditions that go with it. In a study published in April in the journal Diabetes Care, researchers noted a sharp increase in 2020, compared with previous years, of the number of children who showed up at Children’s Hospital Los Angeles with a severe form of new-onset Type 2 diabetes called diabetic ketoacidosis. That might be because children were eating poorer-​quality food and moving less, according to the lead author, Lily Chao, interim medical diabetes director at the hospital. It could also be that worries about the coronavirus induced families to delay seeking treatment for their children’s symptoms until they were in diabetic ketoacidosis.

A better understanding of how and why the pandemic affected children — not just physically but also emotionally and academically — would improve the ability of pediatricians, parents and policymakers to facilitate their recovery. Unfortunately, what is clear is that for children whose B.M.I. increased, “there are no magic bullets,” Black says. And, she adds, “it’s not healthy for kids to think about losing weight.” Rather than try to undo a past B.M.I. increase, a better strategy is to try to slow future ones and establish healthy habits. There is some good news in the fact that children tend to experience a growth spurt during puberty, says Risa Wolf, a pediatric endocrinologist at the Johns Hopkins Hospital; this can enable them to redistribute added weight on a taller frame. Wolf suggests parents focus on trying to build physical activity into their kids’ daily routine; the C.D.C. recommends 60 minutes for school-age children. And cutting fruit juice and soda from children’s diets is an easy way to significantly reduce sugar and calorie intake, Chao says.

But the Pediatrics findings, Jenssen argues, also highlight how the problem of obesity can come from societal causes: The children who had the largest B.M.I. increases in his study were 5- to 9-year-olds. “They’re not making those individual choices,” he says. “They’re influenced by the environment.” Which means policies that improve the post-pandemic availability of nutritious meals and recreation can still positively influence their trajectory. Rebecca Franckle, a public health researcher at Boston College, was an author of a May report about how pandemic adaptations could be expanded to improve U.S.D.A. summer feeding programs for Healthy Eating Research, a nonprofit organization. “There’s huge opportunity,” she says, “for prevention when it comes to kids versus adults.”

Kim Tingley is a contributing writer for the magazine.