Kids who are overweight or obese often struggle with schoolwork, and now new research provides clues on how excess weight may harm the developing brain.
“The main takeaway is to raise awareness about brain health consequences of obesity besides physical health consequences, especially since obesity rates are very high and continue to rise,” says study author Simone Kaltenhauser, a post-graduate research fellow in radiology and biomedical imaging at the Yale School of Medicine in New Haven, Conn.
About one in every five American kids is now obese, according to the U.S. Centers for Disease Control and Prevention.
What the study shows
For the study, researchers looked at several types of brain scans in more than 5,100 kids aged 9 to 10 who took part in the ongoing Adolescent Brain Cognitive Development (ABCD) study. Of these, 21% were overweight and 17.6% were obese.
What did they find? There were structural and functional brain impairments in kids who were overweight or obese when compared to kids who weren’t, and these changes could contribute to poor academic performance.
Specifically, kids who were overweight or obese showed a thinning of the outermost layer of their brain (the cortex), and this has been linked with impaired executive functioning skills, such as planning and juggling multiple tasks. What’s more, the integrity of the brain’s white matter was impaired in the corpus callosum (which connects the brain’s two hemispheres) and in the pathways within the brain’s hemispheres that connect the lobes of the brain in kids who are overweight or obese.
In addition, brain networks involved in reward-based decision-making and control of behaviors showed reduced connectivity in kids who are overweight or obese.
These patterns persisted over two years, the study showed.
“Our findings provide an important potential explanation of other studies that show higher body mass index [BMI] in children is associated with poor cognitive functioning and academic achievement,” Kaltenhauser says. (BMI is a measure of body fat that takes height and weight into account.)
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Can weight loss help?
It’s too early to say whether weight loss and increased physical activity can offset some of these brain changes, but it is possible, she noted.
“Brain plasticity, or the ability to reorganize neural pathways of children, is very high, and there is evidence in the literature that cognitive performance may increase after weight-loss interventions,” Kaltenhauser notes. “The ongoing ABCD study will collect data from its participants for several more years, which will allow us to further track these changes over time.”
Dr. Vincent Mathews says the new study helps to connect some dots between excess weight and brain changes in kids. “Prior research has shown that obesity is associated with poorer academic performance, impaired cognitive function, and lower brain volume in children,” according to Mathews, chairman of radiology at the Medical College of Wisconsin in Milwaukee.
“This study shows changes in brain function and the integrity of white matter tracts related to childhood obesity, which potentially explain the impaired cognitive function and its effect on academic performance,” Mathews adds.
Some questions remain, he says. “It isn’t clear whether obesity precedes brain function impairment or if the latter precedes the development of obesity at this time,” Mathews stresses.
Dr. Scott Kahan, director of the National Center for Weight and Wellness in Washington, D.C., says that most of the data on how obesity affects brain health is in adults. “This study adds to the literature base in kids,” he notes.
More research is needed to see if carrying excess weight directly impacts the brain, or if an unhealthy diet and/or lack of physical inactivity are the culprits, or whether factors that predispose people to obesity, such as lower socioeconomic status, also contribute to poor brain development, Kahan says.
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How you can help your child
There is no one solution to address obesity, but as a parent, you can help your child maintain a healthy weight and set up lifelong healthy habits at home by doing the following, according to the CDC:
Model a Healthy Eating Pattern
Frozen and canned fruits and vegetables are often less expensive than fresh and still good for you.
Look for low-sodium or no salt added vegetables and fruits packed in 100% fruit juice.
Adopting healthy eating patterns as a family will help your child reach and maintain a healthy weight as they age. Eating a variety of vegetables and fruits, whole grains, lean protein foods, and low-fat and fat-free dairy products and following nutrition guidelines will set your family up for optimal health.
You can make sure your child gets the nutrients he or she needs by making half their plate fruits and vegetables. Help them rethink their drink by replacing sugary drinks, such as soda, fruit drinks, and flavored milk, with water, 100% juice, or plain low-fat milk.
Move More as a Family
Physically active youth have stronger muscles and bones, better cardiovascular fitness, and lower body fat than those who are inactive. Children aged 3–5 years should be physically active throughout the day. Children aged 6–17 years need at least 60 minutes of physical activity every day.
Help your children move more and meet the Physical Activity Guidelines for Americans by making it a family affair. Walking the family pet before and after school, riding bikes, and having races in the yard all count toward physical activity. Active chores, such as washing the car, vacuuming a room, or raking leaves, also count.
Set Consistent Sleep Routines
Good sleep helps prevent type 2 diabetes, obesity, injuries, and problems with attention and behavior. If your child isn’t getting enough sleep, he or she is at risk for unhealthy weight gain. Researchers are still trying to learn how sleep is linked to weight gain. Some reasons might include causing a child to eat more or to be less physically active due to a lack of energy.
How much sleep does your child need? Preschoolers need 11–13 hours of sleep per day, including naps. Children 6–12 years old need 9–12 hours of uninterrupted sleep a night, and youth 13–18 need 8–10 hours. Sticking to a consistent sleep schedule, including on weekends, can help your child sleep better.
Replace Screen Time with Family Time
In young people, too much screen time can lead to poor sleep, weight gain, lower grades in school, and poor mental health. Reducing screen time can free up time for family activities and can remove cues to eat unhealthy food.
Try turning your child’s screens off an hour before bed and removing screens from their bedrooms. This can help reduce screen time and improve sleep. The American Academy of Pediatrics recommends creating a family media plan with examples of how to reduce screen time.
If you are concerned about your child’s weight and health risks, speak with your child’s healthcare provider. He or she may be able to help you come up with other solutions for tackling excess weight.