Oct 5, 2022 – What if a baby’s brain developing at the critical time just before birth and in the first days afterwards poses a lifelong risk of obesity?
Previous research has indicated that the human genes associated with obesity determine whether a person will have difficulty maintaining a healthy weight later in life. For decades, researchers have looked for links between genetic variants and body mass index (BMI), explains Robert Waterland, PhD, professor of pediatric nutrition at Baylor College of Medicine in Houston, Texas. But the problem is that the genetic links found so far do not explain weight gain and who is most at risk, he says.
Could there be more reasons for the high rates of obesity than genetics and lifestyle factors?
In their new study published in science progressWaterland and his team studied the possibility that environmental influences – such as poor diet and stress – during a critical period of brain development may influence obesity risk.
The research team, led by Harry Mackay, PhD, a postdoctoral fellow in pediatrics and nutrition at Baylor, focused on a small part of the brain called the arcuate nucleus of the hypothalamus, which regulates the body’s energy balance between food intake, physical activity and metabolism.
They studied mice in the first few weeks of life and found that the arcuate nucleus undergoes intense growth at a critical period of time when brains are particularly sensitive to programming, which will later determine how well the body senses whether it is hungry and when the body has enough food.
The scientists focused on epigenetics and worked to bookmark genes that would not be used in different cells. A big surprise in the research came when the researchers compared their epigenetic data in mice to human data and found that the target regions for epigenetic maturation in the mouse arcuate nucleus strongly overlap with the human genomic regions associated with BMI.
Waterland says that although the work has not delved into when epigenetic changes occur in humans, previous research has shown that they occur earlier in humans than in mice.
“My hunch is that the same epigenetic development that we documented in early postnatal mice actually occurs during late fetal development in humans,” he says.
If this is the case, “a major concern is the extremely high prevalence of maternal obesity in the United States and many developed countries of the world,” which may affect the health of newborns.
If future weight problems start before birth or in those first weeks of life, some may feel doomed to obesity. But Waterland says the focus on genetics in previous research hasn’t been particularly encouraging because it’s so difficult to change your genes.
“At least if we understand how the environment affects development, then at least we can look for ways to improve that in the future,” he says.
Waterland explains that it’s too early to say whether obesity is actually a neurodevelopmental disorder, but if early research like this continues to build evidence, public health interventions to reduce the worldwide obesity epidemic could focus more on prenatal nutrition And early in life, healthy weight gain, and reduced stress.