Oct 5, 2022 – What if a baby’s developing brain during the critical period just before birth and in the early days thereafter sets lifetime risk for obesity?
Previous research has shown that human genes associated with obesity determine whether a person will find it difficult to maintain a healthy weight later in life. Researchers have been looking for links between genetic variants and body mass index (BMI) for decades, explains Dr. Robert Waterland, Professor of Pediatric Nutrition at Baylor College of Medicine in Houston, TX. But the problem is that the genetic links found so far don’t explain the weight gain and who’s most at risk, he says.
So could there be more to rising obesity rates than genetics and lifestyle?
In their new study published in scientific advancesWaterland and his team investigated the possibility that environmental influences – such as poor diet and stress – could influence obesity risk during a critical window in brain development.
The research team, led by Harry MacKay, PhD, a postdoctoral researcher in pediatric nutrition at Baylor, focused on a tiny section of the brain, the arcuate nucleus of the hypothalamus, which regulates the body’s energy balance between food intake, physical activity and physical metabolism .
They studied mice in the first few weeks of life and found that the arcuate nucleus undergoes rapid growth during a critical time window when the brain is particularly sensitive to programming, which will later determine how well the body senses if and when the body is hungry has enough to eat.
Scientists focused on epigenetics, working to tag which genes are used in different cells and which are not. A major research surprise came when the researchers compared their epigenetic data in mice to human data and found that the regions destined for epigenetic maturation in the arcuate nucleus of the mouse strongly overlapped with human genome regions associated with the BMI are associated.
Waterland says that although the work didn’t address when the epigenetic changes occur in humans, previous research has shown that they occur earlier in humans than in mice.
“My guess is that the same epigenetic development that we documented in the early postnatal mouse actually occurs during late fetal development in humans,” he says.
If this is the case, “the very high prevalence of maternal obesity in the US and many developed countries around the world is a big, big concern” that could affect newborn health.
If future weight problems begin before birth or in the first few weeks of life, some feel condemned to the fate of obesity. But Waterland says the focus on genetics in previous research hasn’t been particularly encouraging either, as it’s very difficult to alter your genetics.
“At least if we understand how the environment affects development, we can at least look for ways to improve that in the future,” he says.
It’s too early to say if obesity is actually a neurodevelopmental disorder, Waterland explains, but if early research like this continues to provide evidence, public health efforts to curb the global obesity epidemic could focus more on prenatal and early childhood nutrition , healthy weight gain, and stress reduction.