Hormones and Your Body: 6 Surprising Effects
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Hormones and Your Body: 6 Surprising Effects

The truth about what hormones really do.

Surprises 1-3

Despite all those tired that-time-of-the-month punch lines, hormones are no joke. Scientists now say that fluctuating hormones can boost your emotional well-being -- and they can exacerbate chronic health conditions and increase your risk of injury while exercising. "They affect your entire body, not just your reproductive system" says Hadine Joffe, MD, director of endocrine studies at Massachusetts General Hospital in Boston.

Surprise #1

Your hormonal shifts may make you susceptible to an exercise injury.

Research suggests that women are four to six times more likely than men to experience a painful knee injury, such as tearing the knee's anterior curciate ligament (ACL), while playing sports such as soccer, basketball, or volleyball. One reason: "Hormones appear to affect a woman's neuromuscular control -- the order and timing in which your muscles contract," says Gregory Dedrick, ScD, an assistant professor in the department of rehabilitation sciences at Texas Tech University Health Sciences Center in Lubbock, Texas. When Dedrick studied women with normal periods, he found that during the first half of their menstrual cycles (when estrogen is the dominant hormone), the way they landed after jumping was off compared to how they landed later in their cycles (when progesterone is the dominant hormone). The timing of the muscles the women used was different, which may help explain their increased risk of injury.

Expert advice: Any time both feet come off the ground -- whether you're dancing or playing soccer -- landing properly can greatly reduce the risk of a knee injury, says Paul Frediani, a personal trainer at Elysium Fitness in New York City. Try to land softly on the pads of your feet, followed by your heels, allowing your ankles, legs, and hips to absorb the shock. "Your knees should be directly over your feet, parallel to the ground, and face the same direction as your toes," Frediani says. And strengthen those hamstrings! "They act as stabilizers to your knees, so the stronger they are, the more your knees are protected," he explains.

Surprise #2

Hormones may affect how turned on your brain gets by smoking and other addictive behaviors.

In a recent study, when researchers had women play slot machines, they found that the female brain circuits linked to pleasure and reward were more active and responsive during the first half of their menstrual cycle than during the second. "This finding may provide insight into menstrual-related mood disorders, and why some women are more vulnerable to addictive drugs during the first part of their cycle," says Karen Berman, MD, chief of the section on integrative neuroimaging at the National Institute of Mental Health in Bethesda, Maryland.

Expert advice: Clearly, many addictive behaviors, such as smoking or relying too heavily on sleep aids, are unhealthy and require a doctor's attention. If you're trying to quit smoking, your doctor may suggest smoking-cessation aids to help you through the tough times. (Exercise is one therapy doctors often recommend.)

Surprise #3

Monthly hormonal changes may cause a health problem to flare up unexpectedly.

Many women report that symptoms of asthma, diabetes, lupus, migraines, and depression are more difficult to control during the last two weeks of their menstrual cycle, a phenomenon known as premenstrual exacerbation. Researchers believe that shifting hormones are to blame. "For some women, a health problem can become unmanageable due to severe premenstrual symptoms," says Diana Dell, MD, an assistant professor of psychiatry and obstetrics-gynecology at Duke University Medical Center in Durham, North Carolina. "We don't know the mechanism, but we see it often enough to know it exists."

Expert advice: Track your symptoms in a journal for at least a month. Mark the start and end dates of your period, then show the journal to your doctor. She may be able to tweak your medication or prescribe an additional one to better control your symptoms, says Dr. Dell.

Surprises 4-6

Surprise #4

Hormones help you bond.

Your brain naturally releases the chemical oxytocin, often called the bonding hormone, since women make more of it when they breastfeed or cuddle a baby. But it's not just for moms! Your body also releases more of this hormone after a 20-second hug, says Louann Brizendine, MD, a neuropsychiatrist in San Francisco and author of The Female Brain.

Expert advice: "You can't hug the people you love too much," says Dr. Brizendine. It's a great way to foster closeness and trust between you and your partner, even when you're feeling less than lovey. And you don't have to restrict your hugs to family. Sometimes the best thing you can do for a friend or close coworker who's reeling from bad news is to listen and reach out with a hug. You'll both benefit.

Surprise #5

Hormones may take the 'zazz out of your sex life.

Testosterone may be a male hormone, but women's bodies also produce it and need it, particularly to encourage sexual desire. Unfortunately for women who report low libidos and may not make enough testosterone to begin with, taking birth-control pills may lower testosterone even more, according to research from the University of Oklahoma in Tulsa. "A woman taking an oral contraceptive may have less of her body's natural testosterone available," says Susan Rako, MD, a psychiatrist in Boston and author of The Hormone of Desire.

Expert advice: If you've noticed a dip in your sex drive since you started taking the pill, talk to your ob-gyn. She may suggest that you try a different formulation. Or you may want to choose a nonhormonal contraceptive, such as the IUD. Unfortunately, there's no way to naturally boost your testosterone levels, and doctors who FITNESS spoke with advised against testosterone supplements. They aren't safe for premenopausal women because they could harm your fetus if you became pregnant, Dr. Rako says.

Surprise #6

You don?t have to live on a hormonal roller coaster as you age.

If you're in your mid to late 40s and your period is irregular and hot flashes and night sweats are taking a toll on you, you're probably experiencing perimenopause. For some women, getting on the pill could provide enough relief from perimenopausal symptoms, says Kathryn Martin, MD, a reproductive endocrinologist at Massachusetts General Hospital and an assistant professor of medicine at Harvard Medical School in Boston. If not, hormone therapy (HT) may offer safe relief. True, previous reports found that HT may increase a woman's risk of heart disease, but the latest advice is that the closer you are to menopause, the more beneficial and less risky HT is likely to be. In fact, new research shows that using HT can lower your cholesterol, help regulate blood glucose and insulin, and keep blood vessels healthy.

Expert advice: Tell your doctor about your symptoms. If you decide to try HT, you'll need to use a nonhormonal contraceptive; although your period may be irregular, you can still conceive.


Estrogen, progester-what? Use this quick definition guide.

Estrogen: An umbrella term for a class of hormones crucial to sexual development and a healthy reproductive system; it can also affect brain function, bone health, and cancer risk.

Oxytocin: This hormone causes contractions during labor, stimulates milk production during breastfeeding, and promotes the mother/child bond. Its feel-good power could even strengthen your relationship with your partner and other close contacts.

Progesterone: Produced in the ovaries, especially during the second half of your menstrual cycle, it stimulates the thickening of the uterine lining in anticipation of a possible pregnancy.

Testosterone: Typically thought of as a male hormone, testosterone is also produced in women's bodies to promote sexual desire, and it plays a role in hair growth and energy levels.

Effects of Everyday Habits

These everyday habits influence your hormones:

Exercising regularly: This disease-beating habit has been found to help keep hormones, including estrogen, at a healthy, stable level, thus lowering cancer risk.

Eating healthy: If you're underweight, you're likely not producing enough estrogen, which can raise your risk of osteoporosis. Carrying extra pounds can stimulate too much estrogen, increasing your risk of breast cancer. A balanced diet that includes no more than 35 percent of calories from fat (mostly the heart-healthy vegetable and lean-protein kind) can help your body maintain ideal hormone levels.

Smoking: Lighting up causes you to produce less estrogen, a risk factor for osteoporosis. Smokers also tend to experience menopause two years earlier than nonsmokers (also due to less estrogen), which ups heart disease risk.

Drinking too much: Indulging in more than one alcoholic drink per day is associated with too-high estrogen levels, which can increase breast cancer risk.

Age-by-Age Guide to Hormones

How your hormones change as you age:

Your 20s: The nice-and-easy decade

This is the time of relative stability for your hormones, says Geoffrey Redmond, MD, an endocrinologist in New York City and author of It?s Your Hormones. Your menstrual cycle has likely hit its stride, with estrogen and progesterone rising and falling in predictable patterns, meaning that you can now anticipate your PMS (and soothe it before it blows up). What?s more, your body?s response to hormones is less dramatic now, which is why menstrual cramps may be less intense than they were during your teens.

Your 30s: The more-havoc decade

For reasons experts don?t understand, your brain may become sensitive to your menstrual cycle's usual hormonal fluctuations, thus triggering more PMS symptoms. And for many women, this is the prime baby-making decade, which can equal a hormonal roller coaster. In fact, hormones can remain in flux for up to a year after childbirth, particularly if you breastfeed.

The upside: In your mid to late 30s, your body may have more available testosterone, which increases libido and sexual satisfaction, says Susan Rako, MD.

Your 40s: The perimenopause decade

Although many women won't hit menopause until their 50s (the average age is 51), the long transition that a woman?s body makes as she moves toward it, known as perimenopause, can last four to five years. The result: Estrogen and progesterone levels can fluctuate wildly, triggering hot flashes, erratic periods, a fuzzy memory, fatigue, and moodiness.

"Half of women experience their first bout of depression during perimenopause," says Louann Brizendine, MD. On a more chipper note: Your levels of the bonding hormone oxytocin also decrease, which from a glass-half-full perspective is a good thing. Now that your body has dialed down your nurturing impulses, you may be better able to focus on your own needs.

Originally published in FITNESS magazine, July 2007.