New researchers has found that boys, and not only girls, may start puberty earlier than average if they are obese.
Carried out by researchers from the University of Chile in Santiago, the new study looked at 527 Chilean boys ages 4 to 7 years.
The researchers measured their total body obesity using body mass index (BMI), as well as central obesity, or excess belly fat, by measuring the waistline.
To assess when puberty started the researchers used a standard measure for boys.
The findings, which were presented on Sunday at ENDO 2019, the Endocrine Society's annual meeting in New Orleans, USA., showed that both total obesity and central obesity increased the chance of early puberty, compared with having a healthy weight.
For example, at age five or six, boys with total obesity had nearly 2.7 times higher odds of starting puberty early before age nine, and those with central obesity had almost 6.4 higher odds.
The average age at onset of puberty for this group was 11.4 years.
Lead investigator, Maria Veronica Mericq, M.D. explained that central obesity may increase the risk of early puberty even more than total obesity as central obesity is more closely related to fat mass, whereas a higher BMI, the measurement used for total obesity, can reflect increased muscle not just fat, especially in athletes.
Previous studies have shown that obesity is linked to an earlier puberty in girls, but the findings from studies on boys have been less clear.
Some studies have found that both being overweight and obesity delay puberty in boys, while others have linked being overweight, but not obese, to earlier puberty.
"With the increase in childhood obesity worldwide, there has been an advance in the age at which puberty begins in girls. However, in boys the evidence has been controversial," said Mericq.
"Early puberty might increase the risk of behavior problems and in boys could be related to a higher incidence of testicular cancer in adulthood. Our results suggest that controlling the obesity epidemic in children could be useful in decreasing these risks."