Internationally Adopted Children Hit Puberty Earlier, Study Finds

But are internationally adopted children really more at risk?

"It depends on their country of origin and on their living conditions up until their adoption," says Hélène Delisle, a professor at the Université de Montréal's Department of Nutrition.

"Many factors are at play, but a low birth weight that isn't recuperated between the ages zero and two, combined with an accelerated weight gain during childhood, would increase the risk of early puberty and chronic disease in adulthood."

In Quebec, half of the 900 children who are internationally adopted every year are from China. Some girls begin puberty as early as eight and boys as early as 10-years-old.

Here's how it works: The beginning of puberty is greatly correlated to weight. Weight gain provokes the secretion of leptin, a hormone that plays a key role in regulating appetite.

When calorie intake increases, leptin levels also increase which in turn provokes the secretion of GnRH (Gonadotropin Releasing Hormone). This hormone regulates the development of ovulation and the menstrual cycle in women and spermatogenesis in men.

Therefore, a radical change in diet, as is often observed in children migrating to an industrialized country, can trigger puberty. "And many health problems," says Delisle who has studied nutrition on an international scale for more than 30 years.