A new study suggests that physical fitness and body fat may each influence these abilities in different ways. This suggests that body fat mainly influenced how quickly they reacted rather than how often they answered correctly. Because the researchers measured body fat and fitness separately, they could show that each factor had its own independent relationship with brain function. This is important because two children with the same weight can have very different amounts of muscle and body fat. Larger long-term studies and exercise interventions will be needed to confirm whether improving fitness leads to lasting improvements in children’s brain function and behavior.