When your energy intake exceeds your energy expenditure, you are more likely to gain weight. And what is not clearly understood is that half of the body’s energy is consumed by our brain during our early childhood.
Study authors Christopher Kuzawa of Northwestern University and Clancy Blair of New York University School of Medicine said that variation in the energy needs of brain development among children could influence changes in energy expenditure and weight gain.
Kuzawa said, “We all know that how much energy our bodies burn is an important influence on weight gain. When kids are 5, their brains use almost half of their bodies’ energy. And yet, we have no idea how much the brain’s energy expenditure varies between kids. This is a huge hole in our understanding of energy expenditure.”
The author added, “A major aim of our paper is to bring attention to this gap in understanding and to encourage researchers to measure the brain’s energy use in future studies of child development, especially those focused on understanding weight gain and obesity risk.”
The authors explained that it is unclear whether programs designed to stimulate the development of the brain through enrichment, such as preschool programs, might affect the brain’s pattern of using the energy.
Kuzawa said, “We believe it plausible that increased energy expenditure by the brain could be an unanticipated benefit to early child development programs, which, of course, have many other demonstrated benefits. That would be a great win-win.”
This new speculation was inspired by a 2014 study conducted by Kuzawa and his team that showed the brain consumes nearly two-thirds of the body’s resting energy expenditure, while by the age of five, it is almost half of the total expenditure. They also found that ages when the energy needs of the brain increase during childhood are also ages of declining weight gain.
Kuzawa and his team concluded that the rate of weight gain increased as the energy needed for brain development reduced in children and adolescents. He said, “This finding helped confirm a long-standing hypothesis in anthropology that human children evolved a much slower rate of childhood growth compared to other mammals and primates in part because their brains required more energy to develop.”