How WEIGHT Can Affect Puberty: Obese girls are more likely to start their periods earlier, but breasts develop more slowly, study finds
- Researchers studied 90 girls between 8 and 15 years old, 36 were obese
- Previous studies have shown that obese girls enter puberty earlier
- Obese girls had higher levels of some important hormones than skinny girls
- Linked to slow breast maturation, irregular periods, acne and excess body hair
Obese girls approaching adolescence have elevated hormone levels that can cause them to start their periods earlier than their leaner peers, a new study finds.
Overweight girls are also at an increased risk for irregular menstrual cycles, delayed breast development, acne, and excessive body hair during puberty.
Previous research has also found that fatter youngsters start puberty earlier, but the new study is the first evidence why this may be the case.
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Overweight girls are more likely to develop acne and excessive body hair during puberty than their leaner peers, a study claims (stock)
Researchers from the National Institute of Environmental Health Sciences (NIEHS) studied 90 girls between 8 and 15 years old, 36 were obese and 54 were of ‘normal’ weight.
They were followed regularly for four years by clinicians who performed ultrasounds on their breasts and pelvic regions, and also measured hormone levels from blood samples. Each girl also revealed when they had their first period.
“Girls with greater total body fat showed higher levels of some reproductive hormones, including follicle-stimulating hormone (FSH), inhibin B, and male-like hormones such as testosterone,” said lead author Dr. Natalie Shaw.


US study found that girls who carry too much puppy fat during their teenage years have different hormone levels than someone of ideal weight (stock)
She adds that girls with higher body fat content, as determined by a dual-energy X-ray absorptiometry (DXA) scan, were also younger at the time of their first period and had delayed breast maturation.
However, body fat and subsequent altered hormone levels were found to have no discernible influence on uterine and ovarian development.
Dr. Shaw adds, “The long-term consequences of these differences in markers for puberty merit further investigation.”
The research is published in the Journal of Clinical Endocrinology & Metabolism.
A 2007 study followed 354 girls through puberty and found that obese girls had an 80 chance of having their first periods before the age of 12.
A link between weight and puberty has long been seen, but this was one of the first studies to show that weight likely caused early puberty, and not the other way around.
However, a 2017 study by Imperial College London found that girls who enter puberty earlier are also more likely to be overweight as adults.
According to Dr. Dipender Gill, lead author of the Imperial study, this was evidence that early puberty causes obesity in adulthood.
Both Dr. Gill and Dr. Joyce Lee, lead author of the 2007 study at the University of Michigan, believe they have identified causality, indicating that childhood obesity causes early puberty and in turn causes obesity in adults.
Although the relationship had come about, the exact cause of it remained unknown.