Obesity is undeniably one of the United States’ most pressing public health issues. The reasons why people have gained so much weight, however, are a bit more controversial. Some believe that obesity is almost entirely preventable, a result of unhealthy lifestyle choices such as lack of physical activity and overeating. Others point to possible genetic factors, citing situations where overweight people exercise and eat right but still cannot lose weight. New research may contribute to the argument that biological factors add to obesity — obese teens already show signs of hormonal differences from their average-weight peers.

The study, published in the Journal of Clinical Endocrinology & Metabolism, found that obese teens have lower levels of spexin, a hormone potentially involved in weight management. Adult studies have suggested it is tied to regulating the body’s energy balance and fat mass.

“Our study is the first to look at levels of spexin in the pediatric population,” said Dr. Seema Kumar, one of the study’s authors from the Mayo Clinic in Rochester, Minn., in a press release. “Previous research has found reduced levels of this hormone in adults with obesity. Overall, our findings suggest spexin may play a role in weight gain beginning at an early age.”

Obesity, which occurs when a person has a body mass index at or above the 95th percentile, affects about 17 percent of children in the U.S., according to the Endocrine Society. Childhood obesity in particular is associated with a cost of $14.1 billion per year for prescription drugs, emergency room visits, and outpatient care. The condition is also linked to cardiovascular disease, diabetes, and bone and joint problems.

The current study examined 51 obese and 18 normal-weight teens. The researchers analyzed the spexin levels in the teens’ blood, then divided participants based on this level. Among those with the lowest amount of the hormone, the chances of having obesity were 5.25 times higher than in the group with the highest levels.

Previous research has suggested the hormone produces weight loss in rodents; higher levels led to a reduction in food consumption and increased physical activity.

“It is noteworthy that we see such clear differences in spexin levels between obese and lean adolescents,” Kumar said. “Since this is a cross-sectional study, more research is needed to explore the physiological significance of spexin, how it may be involved in the development of childhood obesity, and whether it can be used to treat or manage the condition.”

Source: Kumar S, Hossain J, Nader N, Aguirre Castaneda R, Sriram S, Balagopal B. Decreased Circulating Levels of Spexin in Obese Children. Journal of Clinical Endocrinology and Metabolism. 2016.