New Genetic Test Can Identify Children's Obesity Risk as Adults

A groundbreaking new genetic test may help kids develop healthy habits early on by identifying those who are at increased risk of obesity as adults, according to an article published in the journal Nature Medicine.

The test, which can be used to predict adult obesity in children as young as five, could one day give parents and doctors the opportunity to intervene before young people become weighed down by extra pounds.

According to data from the federal Centers for Disease Control and Prevention, more than 2 in 5 adults are obese in the United States today. That number is projected to grow to 2 in 3 by 2050.

Obesity greatly increases the risk of serious health problems, including heart disease, diabetes, stroke, nonalcoholic fatty liver disease, cancer, and mental health disorders.

Over 600 scientists from around the world analyzed the genetic data of more than 5 million people to develop the test.

Ancestry-specific "polygenic risk scores" were then created, which add up thousands of gene variants linked to a higher adult body mass index, to estimate someone's chances of becoming obese.

"What makes the score so powerful is its ability to predict, before the age of five, whether a child is likely to develop obesity in adulthood, well before other risk factors start to shape their weight later in childhood," Roelof Smit, a genetic epidemiologist at the University of Copenhagen, said in a statement. "Intervening at this point can have a huge impact."

The tool's performance has been impressive thus far for those of European descent, explaining approximately 17.6% of the risk for developing obesity.

"That's a pretty powerful risk indicator for obesity, but it still leaves open a lot that is unknown," Dr. Roy Kim, a pediatric endocrinologist who did not participate in the study, told NBC News.

But more than 80% of the risk for developing obesity is still determined by what people eat, how much they exercise, and where they live.

According to the researchers, the test was about twice as effective as the methods doctors currently use to gauge obesity risk.

For people of non-European ancestry, however, the polygenic risk score did not perform as well, explaining just 2.2% of obesity risk in rural Ugandan populations, for example.

Researchers said the performance gap is likely due to a lack of diversity in the genetic data used to build the test and increased genetic variation in African populations.

The genetic data of more than 5 million people was used, with 71.1% of European descent, 14.4% of American descent, 8.4% of East Asian descent, 4.6% of African descent, and 1.5% of South Asian descent.