Puberty and Eating Disorders- The Perfect Storm
Puberty sucks. Let’s just get that out of the way. Your body is changing, sprouting breasts and zits at the most inopportune of times. The angst of being more or less “developed” than your friends (hello, locker room comparisons!) is difficult. Then there are the psychosocial changes. Your peer relations grow much more complicated, you are expected to juggle more tasks, to figure out who you are. None of this is easy.
Mostly, researchers thought that the onset of EDs at around the time of puberty was due to psychosocial factors: not wanting to grow up, finding peer relations too complicated, the increase in body awareness and dissatisfaction. No one doubts that these can be significant factors in the development of EDs, especially if puberty tends to happen slightly earlier than average. But there’s also something about the chemical and hormonal changes of puberty that alter a person’s risk of developing an eating disorder.
In a recent paper in Hormones and Behavior, Kelly Klump reviewed what we know about puberty, eating disorders, and disordered eating. Especially in females, the surge of sex hormones seems to activate underlying genetic risk factors and alter neurochemistry. Although researchers still aren’t sure exactly what is going on, they are collecting a vast body of evidence that puberty is a particularly high risk period for EDs.
What happens at puberty?
First off, I should probably clarify things about what hormones are and what they do. Below, in all of its splendor, is estradiol, one of the estrogens (there are three: estriol, estradiol, and estrone):
Ask Hollywood, and estrogen is one of those magic chemicals that make women weep at Hallmark commercials. Well, no. A slightly more accurate example is that estrogen is responsible for secondary sex characteristics in females. Okay, yes, but how does estrogen do that? Estrogens are produced by the ovaries and by adipose tissue, and they are secreted into the blood stream and travel to cells throughout the body that have receptors for them. No receptor, and it’s as if the estrogen is locked out of the house. If the cell does have a receptor, the estrogen enters the cell and heads to the nucleus. Once in the nucleus, it serves to switch genes on and off. Breast cells have estrogen receptors, and so do our brain cells. Estrogen helps to control neurotransmitter production–which can explain why some women get weepy before their periods (others of us get cranky and mean, but that’s another story).
The risks of a variety of neuropsychiatric disorders increase during puberty, of which eating disorders are only one. The prevalence of anxiety and depression appear to increase during puberty, especially in girls (Cyranowski et al., 2001). Researchers also found that early puberty and going through puberty more rapidly was associated with later anxiety and depression (Marceau et al., 2011)
In terms of ED risk, there appear to be a number of factors at work during this time period. For one, Klump found that many ED sufferers (especially those with BN and EDNOS) report showing signs of puberty at an earlier age and/or being more developed than their peers. This could obviously lead to teasing, discomfort with one’s body (especially when your friends are still sticks), and generally negative social comparisons that then lead to disordered eating. There could also be something more related to hormone exposure at an earlier age, but no one has really tested that, although there are relationships between estradiol levels and ED symptoms, but I’ll get to that later.
Klump herself also used twin studies to look at how puberty affects disordered eating (Culbert et al., 2009). Klump and colleagues looked at a set of 656 female twins, who they followed from birth through young adulthood as part of the Minnesota Twin Family Study and the Michigan State University Twin Registry. The researchers assessed for ED symptoms when the girls were between the ages of 10-15, and again when they were young adults. They found that, for twins that hadn’t yet showed signs of puberty, genetics explained very little of why some of these twins had high levels of disordered eating and the others didn’t. Instead, both individual and broader environmental factors seemed to dominate.
After puberty and into young adulthood, the opposite was true: genetics explain a much larger part of the reason why some of the twins had high levels of disordered eating and others didn’t. You can see the shift on the left-hand figure below.
The right-hand image showed that menarche (first menstrual period) wasn’t as a significant factor as general pubertal status. Another study (also by Klump and colleagues) shows why. It seems that the amount of estradiol in the blood seemed to rule whether genetics were the most important factor. Twins between ages 10-15 with low estradiol levels (thus not truly in puberty yet) showed little genetic effects on disordered eating while twins in the same age group but with high estradiol levels showed much higher genetic effects (Klump et al., 2010). Animal studies have shown that puberty also increases the likelihood of recurrent binge eating.
Interestingly, the hormonal effects of puberty seem to be limited to females. Studies on males have generally show much less of an influence of puberty than in women. Historically, people have cited the influence of advertising and the media as to why women have suffered from EDs at much higher rates than men. While these studies can’t (and shouldn’t) discount all effects from the media, they do show that this explanation is over-simplistic. Female sex hormones also significantly increase risk of disordered eating and eating disorders.
Other studies provide clues, too. Early puberty increases disordered eating and anxiety levels in both males and females, although it didn’t appear to increase risk-taking behavior and substance abuse.
Other studies have found links between other mental disorders and early puberty as well. So early puberty may not only directly increase disordered eating behaviors, it increases risk for other psychological problems that are strongly associated with EDs, too.
In her review article, Klump shared two main theories as to why puberty would be associated with ED risk:
1. Activational. Transient effects that depend on the presence/absence of hormone
2. Organizational. Permanent effects that persist beyond the period of exposure to hormone and program later activational responses to hormone
Klump says that the evidence seems to support organizational effects since this model predicts 1) hormones organize behavior during puberty through permanent changes in brain structure/function; and 2) these changes organize the brain to respond to circulating levels of hormones in adulthood which activate and/or influence the expression of behavior.
Exactly what the estrogens do to increase ED risk isn’t clear. No one knows what genes they switch on and what effects on behavior they might have. Some have hypothesized that the earlier age of ED onset may be partially linked to earlier ages at menarche in girls.
Puberty is a very complicated time, and the research surrounding EDs and puberty is equally as complicated. Still, I hope I’ve at least given you an idea of what researchers think might be happening during this time period that seems to have a significant effect on eating disorders.
Culbert, K. M., Burt, S. A., McGue, M., Iacono, W. G., & Klump, K. L. (2009). Puberty and the genetic diathesis of disordered eating attitudes and behaviors.Journal of abnormal psychology, 118(4), 788. doi: 10.1037/a0017207
Cyranowski, J. M., Frank, E., Young, E., & Shear, M. K. (2000). Adolescent onset of the gender difference in lifetime rates of major depression: a theoretical model. Archives of General Psychiatry, 57(1), 21. doi:10.1001/archpsyc.57.1.21.
Klump, K. L. (2013). Puberty as a critical risk period for eating disorders: A review of human and animal studies. Hormones and behavior, 64(2), 399-410. doi: 10.1016/j.yhbeh.2013.02.019
Klump, K. L., Keel, P. K., Sisk, C., & Burt, S. A. (2010). Preliminary evidence that estradiol moderates genetic influences on disordered eating attitudes and behaviors during puberty. Psychol Med, 40(10), 1745-53. doi: 10.1017/S0033291709992236
Marceau, K., Ram, N., Houts, R. M., Grimm, K. J., & Susman, E. J. (2011). Individual differences in boys’ and girls’ timing and tempo of puberty: Modeling development with nonlinear growth models. Developmental psychology, 47(5), 1389. doi: 10.1037/a0023838