By Robert Preidt
Researchers at Imperial College London analyzed data from hundreds of thousands of women in the United Kingdom. They said their findings add to evidence linking onset of puberty with adult women's weight.
Previous findings were observational and could have been affected by factors such as ethnicity, economic background, education level and diet. That would make it hard to tell whether early puberty or other factors affected women's weight, according to the study authors.
They said their findings show that early puberty is itself a risk factor for women being overweight.
"Previous studies have shown there is an association, but we didn't know whether early puberty caused obesity in adulthood, or was simply associated with it. In our latest study we've generated evidence to support that it is a causal effect," study first author Dipender Gill said in a college news release.
Gill is a research fellow in the School of Public Health.
The study authors said it's not clear why early puberty might trigger obesity in adult women. They suggested that gaps in physical and emotional maturity may play a role. Girls who mature earlier may be treated differently or face different societal pressures than later-maturing girls.
Another possibility is that the physical effects of hormone changes during puberty -- such as breast growth -- affect a girl's chances for excess weight later on.
"It is difficult to say that changing someone's age of puberty will affect their adult risk of obesity and whether it is something that we can clinically apply -- as it would unlikely be ethically appropriate to accelerate or delay the rate of puberty to affect BMI," Gill said.
"But it is useful for us to be aware that it's a causal factor -- girls who reach puberty earlier may be more likely to be overweight when they are older," he added.
The study was published recently in the International Journal of Obesity.