The August 2004 issue of National Geographic Magazine features a story on the growing epidemic of obesity in America.  Alarming statistics in the article show that the rate of obesity in American children has tripled since 1980.  Most parents are aware of the health hazards associated with overweight children; however, one aspect of obesity in children that is often overlooked is the effect that high levels of weight and body fat play on hormone balance.  In particular I want examine this effect on young girls.

As a psychiatrist who sees adolescents, parents often ask me why girls today are maturing earlier than the previous generation.  This phenomenon is quite easy to spot if you look around at malls and schools in your community.  More girls today are entering puberty at younger ages.  I have seen girls six years old who are developing breasts.  Could weight be a factor in this hormone acceleration?

During the 1800’s the average age to begin menstruation was seventeen.  Ten years ago 20% of Caucasian girls by age eight were beginning to show beginning signs of puberty (breast buds and pubic hair).  Today 50% of African-American girls have started puberty by age eight; another 20% reach puberty by age seven.  Hispanic girls also show patterns of early puberty close to that of African-American girls.  How might obesity be a major culprit in this growing phenomenon?

American girls generally enter puberty between ages nine and fourteen.  Puberty any earlier than this is called premature (or precocious) puberty.  Puberty can be divided into three stages: the beginning of breast development (breast buds) signals thelarche—the first stage.  Adrenarche—the second stage, is triggered by the release of androgens (sex steroids) from the adrenal glands.  This is accompanied by the appearance of pubic hair, axillary hair, oily skin and increased acne.  Menarche—the third stage, is the beginning of menstrual periods.  Recent research suggests weight and percentage of body fat sets in motion this chain of events.

The average age of puberty has been dropping every decade steadily since the 1800’s.    Weight and body fat percentages have been steadily increasing during this period as well.  This change is attributed to better nutrition.  Today thin girls begin puberty later than overweight girls.  However, the ratio of body fat to weight appears to be the precipitator of these hormonal changes rather than weight alone.  Forty-seven kilograms (100 pounds) is the average weight of a female beginning menarche.  Body fat ratios of 20-25% are present in these females as well.  When body fat percentage drops below a certain level (as witnessed in anorexia nervosa) females stop menstruating no matter what their weight.  The last two decades America has seen an explosion in the weight and body fat of both boys and girls.  This generation is the heaviest in the history of the world!

Numerous health risks accompany premature puberty.  Let’s look at these.

Physical health: Early puberty in girls increases the risk of Polycystic Ovarian Syndrome (PCOS), a disease characterized by loss of menstrual periods, infertility, obesity, and excessive body hair growth.  Adolescent and adulthood obesity risks are increased which in turn increases the incidence of diabetes.  The risk of emerging breast and uterine cancers are heightened as well due to increased exposure to estrogen.

Psychological health: Girls enter the psychological stage of latency between ages 6-10.  During this stage girls avoid boys like the plague and consider them all to be “creepy.”  This phase is marked by close friendship with other girls and as sense of mastery in school and other school related activities.  Girls especially need these years to develop a strong sense of self.  If the physical changes of puberty come too early, it gives girls confusing signals.  Their body begins to attract boys like flies on sugar, but their mind is still in latency not wanting anything to do with boys.  They develop the body of a young woman while their mind is still that of a child.

Sociological-cultural health: Premature puberty sets ominous pitfall for girls.  They are teased by boys their own age, but get increased sexual overtures from older boys, which can lead to a difficulty in maintaining independent identity.  These girls also become defined by how they look rather than who they are, which often lowers self-esteem and sense of self-worth.  In addition to changing the body these hormones also start up the sexual drive.  Adolescent sexual urges in the mind of a child can wreak devastating consequences.  Girls who look seventeen when they are twelve are under much pressure from older boys to engage in risky behaviors like smoking cigarettes and experimenting with drugs and alcohol.   Girls who sexually develop too early experience more sexual harassment, increased risk of date rape, and an earlier vulnerability to accidental pregnancy than their normal developing counterparts.  These factors are no doubt a large reason why America is today having a crisis with the number of pre-teen pregnancies skyrocketing. 

 In summary hormones are both marvelous and maddening.  Marvelous when they allow our body, mind, and spirit to function at its best and maddening when they are out of proper balance.  Hormone problems are easy to overlook because they are usually not visible like a broken leg.  If you have a young girl who is overweight I encourage you to be assertive in getting the help you need in confronting this problem.  Start with your family doctor.  If your family doctor isn’t listening, find one who will.  Health care professionals today should be equipped in helping you and your daughter find solutions to childhood obesity.  I urge you to get answers that make sense.  There are too many health consequences if you don’t!