It seems absurd to buy a bra for a 7-year-old. But according to a new study, some overweight young girls now require one.

Because body fat is linked to the production of sex hormones, overweight girls are developing faster than they would if they were a suitable weight for their age—sometimes as early as 7 or 8 years old. According to the Guardian, research shows that “almost one in four black girls and one in 10 white girls had developed breasts by the age of seven.”

In the 1700s, girls usually hit puberty at age 17 or 18 (this delay could have been a result of malnutrition). The physical liabilities of obesity include the increased risk of Type 2 diabetes, heart disease, kidney problems, sleep apnea and other preventable health issues.

But the sexual changes occurring in an obese generation are likely to have emotional and psychological consequences as well. Girls who reach puberty before their peers are more likely to take risks. They’re also more likely to be depressed, have negative body images, suffer from eating disorders, and become sexually active at an earlier age than their peers.

“For the 11-year-old that looks like she’s 15 or 16, adults are going to interact with her like she’s 15 or 16, but so are her peers,” Dr. Frank Biro, author of the study and a doctor at Cincinnati Children’s Hospital Medical Center, told Fox News. Girls who develop at a young age “look physically older,” he said, but “it doesn’t mean that they’re psychologically or socially more mature.”

Girls who develop breasts early might also have a higher risk of breast cancer. Researchers speculate that, beyond weight-related factors, environmental factors could play a role as well. Certain chemicals (such as bisphenol A, which is found in plastic bottles) are suspected of being endocrine disruptors, altering hormones in a way that changes bodily functions.