The Relationship Between the Brain’s Energy and Weight Gain in Children

Mariam Malik ‘22

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Figure 3. Kuwaza and Blair hypothesize a strong relationship between the varying levels of energy the brain needs through growth and development and a child’s BMI.

Around 32% of adolescents and children are overweight or obese in the U.S., according to the National Institutes of Health, and childhood obesity has become a major problem in the U.S. Co-authors Christopher Kuwaza of Northwestern University and Clancy Blair of New York University School of Medicine hypothesized that there is an inverse relationship between brain development and fat disposition in terms of energy expenditure. Changes in energy demands during different developmental stages could be a factor in a child’s weight gain. 

One of these recent studies showed that the brain uses 43% of daily energy requirements (DER) at 4-5 years old, which is 2-3 times more than that of an adult’s brain. This same study also showed that during times when the brain’s energy needs rise, usually in the early childhood stages, the body’s body mass index (BMI) decreases. To further explore this link, the team first looked at changes in body composition and adiposity rebound. Humans’ BMI is the lowest in early childhood and body fat is regained during late childhood and adolescence. This increase in adiposity, or fat tissue, typically occurs around 5-7 years, and this increase in fat is what is known as adiposity rebound. A previous French study found that children who reach this point earlier are more likely to be overweight or obese in adolescence and/or adulthood. Secondly, previous PET and MRI scans have shown that the brain reaches a maximum level of energy expenditure during early childhood, and begins a steady decline into adulthood. Also, evidence has shown that an energy trade-off occurs between brain development and fat disposition through images of reduced grey matter volume in the brain with an increase in BMI. These findings and others have helped the team understand that changes in the brain’s demands of energy are a vital factor in weight gain. 

Kuwaza and Blair hope to spread awareness about how the brain’s energy use influences weight gain in children. But they also hope to facilitate more research on how brain-stimulating enrichment programs might change the brain’s calendar of energy use, as they believe that higher levels of energy expenditure by the brain could be an unexpected benefit of enrichment programs.



  1. C.W. Kuwaza, C. Blair. A hypothesis linking the energy demand of the brain to obesity risk. Proceedings of the National Academy of Sciences 116, 13266-13275 (2019). Doi: 10.1073/pnas.1816908116
  2. Image retrieved from:

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