Excess Body Fat Impacts Puberty Timing In Young Women

Natalie Shaw, MD

New research from a team led by investigators at the National Institutes of Health (NIH) suggests obesity could impact puberty timing and hormones in women.

An analysis of 90 girls aged 8-15 years, results of the analysis suggest girls with greater amounts of total body fat saw the timing of puberty, presence of reproductive hormone levels, and development of reproductive organs develop at a different rate than their counterparts

"We found that in mid- to late puberty, girls with greater total body fat demonstrated higher levels of some reproductive hormones including follicle-stimulating hormone (FSH), inhibin B and male-like hormones such as testosterone. In some girls with higher total body fat, higher testosterone levels were associated with irregular menstrual cycles, acne and excess body hair," said lead investigator Natalie D. Shaw, MD, of the National Institute of Environmental Health Sciences (NIEHS) part of the NIH, in a statement.

While previous epidemiologic studies demonstrating obese girls experience thelarche and menarche earlier than girls of normal weight, investigators noted no studies have investigated how bodyweight impacts clinical and biochemical pubertal biomarkers in this patient population. With this in mind, Shaw and a team of colleagues from the NIH and the Centers for Disease Control and Prevention (CDC) designed the current study to further investigate this transition in girls from the Triangle region of North Carolina.

For inclusion in the study, investigators recruited pre-menarchal subjects with no chronic medical conditions, free from any medications or supplements that might impact puberty, and had no history of precocious puberty or premature pubarche. Additionally, subjects were required to be free from signs of hyperandrogenism. With enrollment taking place between January 2016-September 2020, investigators identified 80 girls for inclusion in their study.

As part of the study protocol, all patients were required to complete at least 1 study visit spaced approximately 8 months apart—the mean number of study visits per person was 2.8±1.7These visits included a complete physical exam with Tanner staging of the breast and pubic hair, breasts ultrasound for breast morphological statin (B-MORPH), and blood and urine collection. Additionally, monarchal status was determined at each study visit and every 3 months by phone until September 2020.

For the purpose of analysis, associations between the aforementioned factors and total body fat were tested using mixed, multi-state, or Cox proportional hazards models adjusted for baseline BMOPRH.

At baseline, normal weight girls were older than overweight or obese girls (11.3 vs 10.2; P <.01) at baseline and had more advanced BMOPRH (P <.01). Results of the investigators’ initial analyses suggest luteinizing hormone, estradiol, and ovarian and uterine volumes increased with time and total body fat appeared to have no effect on this.

Investigators noted an interaction time-total body fat interaction for follicle-stimulating hormone, inhibin B, estrone, total and free testosterone, and androstenedione. In this interaction, levels were initially similar but increased in girls with higher total body fat, plateaued in girls with mod-range total body fat, and decreased in girls with lower total body fat at 1 year. Additionally, results indicated girls with higher total body fat appeared to progress through BMOPRH stage D more lowly but did achieve menarche earlier than girls with lower levels of total body fat.

"In late puberty, girls with greater body fat also showed delayed breast maturation, as determined by breast ultrasound, and earlier menarche. There were no differences in maturation of the ovaries or uterus as a function of body fat,” added Shaw.

This study, “Longitudinal investigation of pubertal milestones and hormones as a function of body fat in girls,” was published in the Journal of Clinical Endocrinology & Metabolism.