Women have it tough.

Every month, we face a recurring cycle that can throw our bodies out of whack and make some of us suffer in many ways. Not only can the ovarian hormones that drive the menstrual cycle makes us emotional, but they may be flipping switches on the genes that make some women more vulnerable to eating disorder symptoms.

In previous research, we determined that there are significant genetic and biological risk factors for eating disorders. My lab was the first to show that ovarian hormones estrogen and progesterone trigger genetic risk for psychiatric disorders in girls and women.

Now, our lab has confirmed that ovarian hormones drive increases in binge eating and emotional eating across the menstrual cycle. We found significantly higher rates of binge eating and emotional eating in the second half of the cycle, when levels of both estrogen and progesterone are high.

These findings fit with prior data in women with bulimia nervosa—in these women, rates of binge eating were 5 times higher in the second half of the cycle than the first half! The scariest part of all of these data is that these substantial increases re-occur monthly. Indeed, as the reproductive cycle repeats itself each month, so does the biological drive to engage in these symptoms.

Once we saw that hormones drive these symptoms across the cycle, the next question for us was—how? How do hormones drive these eating disorder symptoms?  

In our latest study, we think we have determined how and why this is happening, and we have caught the master conductor—ovarian hormones—in the act.

In order to examine the “how and why,” we took a step back and looked into the primary function of hormones in the brain—namely, to regulate genes, or to turn genes on and off and drive physical changes in the body (e.g., the physical changes that occur during puberty) and neural changes in the brain (e.g., increasing or decreasing the synthesis of serotonin). 

Given the significant role of ovarian hormones in gene expression, we began to wonder if the associations between hormones and binge eating were driven by changes in gene expression that then translated into more binge eating and emotional eating during the latter half of the menstrual cycle. Essentially, we wondered if these hormones can change gene functions that trigger psychological symptoms in women, much like they can trigger gene functions that trigger physical symptoms and changes in women.

Our latest research suggests that this is the case. Following the same sample of women across the menstrual cycle, we found that the degree to which genes influence a woman’s emotional eating was up to four times higher in the high-risk hormone phases of the menstrual cycle (the second half of the cycle) than the low-risk phases (the first half of the cycle). In our data, it clearly looked as if changes in genetic risk were accounting for the increases in binge eating/emotional eating symptoms across the cycle that we had observed earlier.

The remarkable piece was that these genetic changes were occurring within days, not months or years. We have known for some time that changes in gene expression can influence behavior, but there was a presumption that this could take months or years. Our data suggest that it can occur over a period of a few days, and that these changes can occur regularly on a monthly cycle.

This important discovery tells us that ovarian hormones are likely at play for other disorders and symptoms that vary across a woman’s cycle, such as anxiety and depression. We may be only seeing the tip of the iceberg in terms of understanding the role of hormones in genetic risk for mental illness.

But we need more research, and we need to understand how these changes may translate into different treatment options for women. These options run the gamut from educating treatment providers and sufferers about the high-risk times of the monthly cycle to designing new biological treatments that may be able to stave off the negative effects of hormones on target genes and neural systems.

Clearly, we are closer to understanding the causes of these disorders than ever before, and we will get there! The women and girls that suffer from these disorders deserve it. 

About the Author

Kelly Klump Ph.D.

Kelly Klump, Ph.D., is a professor at Michigan State University. 

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