New research links children’s fitness and body fat to independent brain development pathways affecting impulse control

A groundbreaking study reveals that aerobic fitness and body fat influence children’s inhibitory control through separate neural mechanisms, challenging traditional views on childhood cognitive health.

Children’s fitness and body composition may shape how well they can resist impulses and filter out distractions, according to new research from Northeastern University. In a study of roughly 100 preadolescent children, investigators found that aerobic fitness and body fat were linked to inhibitory control in different ways, suggesting the two measures may affect developing brains independently rather than as a single package.

Kellyn Carlson, a doctoral student at Northeastern’s Institute for Cognitive and Brain Health who led the work, said greater aerobic fitness was associated with stronger performance on tests of self-control. By contrast, more body fat was associated with more impulsive responding, although it did not appear to reduce accuracy in the same way. The findings were published in Scientific Reports in July.

The study used dual-energy X-ray absorptiometry, or DEXA, to measure body composition rather than relying on body mass index, which the researchers said is a blunt tool for growing children. Charles Hillman, a distinguished professor at Northeastern and director of the institute, called DEXA the gold standard and said it is especially useful in children because growth patterns can change quickly and unevenly. The team also assessed aerobic fitness with a graded exercise test, using oxygen uptake as a measure of how efficiently the body works under exertion.

To test inhibitory control, the children completed a Go/No-Go task while wearing electroencephalogram headsets so the researchers could record brain activity. In the exercise, pupils were trained to press a button for one image far more often than the other, then asked to hold back that response when the rules were reversed. The more aerobically fit children were more accurate on the harder withholding task and showed greater brain activity during both parts of the test. Those with more body fat were more likely to respond impulsively, but not less likely to get the answer right.

The findings add to a broader body of research suggesting that physical fitness and adiposity may influence cognition through different pathways. Earlier studies, including a large reanalysis of childhood fitness and inhibitory control and work linking lower adiposity with better cognitive control, have pointed in a similar direction, while other intervention studies have found that training does not always translate neatly into short-term cognitive gains. Taken together, the new results suggest that both how fit a child is and how much fat they carry may matter for brain function, but not in the same way.