Synopsis
Book by Greene MD Robert A Feldon Leah
Extrait
Chapter one: The Hormone Revolution
Hormones are essentially chemicals secreted in tiny amounts by various glands and tissues in our body that circulate in the bloodstream and ultimately control numerous body functions that occur in cells and organs. While some have been much maligned for turning strong career women into weepy marshmallows and spunky teenagers into monosyllabic sulkers, they are hardly just the troublemakers they’re made out to be. Hormones are, in fact, absolutely essential. They tell us when we need to eat, sleep, drink, warm up, even when to have sex. They strengthen our bones, alert us to danger, and help keep our bodies and brains vital and fully functional—and that’s just for beginners. Hormones, in short, are crucial to our very existence. They are the ultimate coordinators, keeping all our bodily parts and functions regulated and directed toward the same purpose—whether that purpose is as basic as eating or as complicated as reproduction.
But powerful as they are, hormones don’t act on their own. They are in effect handmaidens of the brain, which is the commander in chief of all body operations. As hormones surge through our bloodstream, they’re delivering instructions, generated mainly by our brain, to cells in various sites in our body. (They also deliver information from cells to the brain.) They are the brain’s major intercommunication system for transmitting essential information from cells in one part of the body to cells in another. And there are a lot of them flowing through our body at any given time—we currently know of more than two hundred hormones, and we are constantly discovering more. Within the last ten years, scientists have discovered at least nineteen hormones that help establish and manage appetite and weight alone. And we’ve uncovered a few other surprises that have turned our old concept of hormones upside down and inside out.
NEW FINDINGS
We used to think that hormones were produced only by nine endocrine glands—the thyroid, parathyroid, pancreas, adrenals (2), gonads (2: ovaries and testes), pituitary, and pineal—and that the hormones these glands produced each had only one function. The ovaries and the testes, for example, were thought to be involved solely in reproduction; the adrenals were meant to regulate stress; the pituitary monitored growth; and so on. But over the last decade, we’ve discovered that hormones are not only produced by the endocrine system, but are, in fact, secreted by other parts of our body, as well. Hormones are released by the stomach, skin, bones, white blood cells, even our extra belly fat—in fact, almost every part of the body can produce some hormones. That makes for a lot of chemical messages running through our body and a lot of hormonal interaction. Contrary to old-school thinking, no hormone is an entity unto itself. Each one impacts the others, and that mutuality plays a huge role in the way you feel on a day-to-day basis. There are four major hormone groups in terms of function and what they do for you, and even though they cross over into other territories, these categories are their home ground:
Sex hormones (estrogen, testosterone, and progesterone) are the big guns—the hugely important hormones produced by your ovaries that we’ll be focusing on throughout the book. As a woman, the levels of your sex hormones shift more frequently and more dramatically than most of your other hormones, creating a delicate balancing act with one another and with every other hormone in your body. We’ve always known that the sex hormones influence reproductive status and define gender, but we’ve only recently discovered that they are much more all-encompassing than had been previously considered. The powerful effects of estrogen on the brain; the rather limited abilities of progesterone in areas other than the uterus; and testosterone’s ability to help build muscle, regulate sexuality, and act as a building block of estrogen coalesce to form a fragile relationship that has a tremendous impact on your mental, physical, and emotional well-being. Sex hormones are, in fact, largely responsible for establishing and maintaining a considerable part of adult functioning.
The metabolic hormones (aka energy hormones): This group, which targets all metabolic processes and monitors and regulates our physiology, includes the thyroid hormones, insulin, growth hormone (GH), and many others. Their job is to regulate how we use our calories—the ones from our most recent meal as well as the ones we’ve stored as fat. They decide if we need to store our calories, use them to build more tissue, or burn them to keep warm. And they ensure our health and survival by monitoring our need for energy.
Regulatory hormones: These hormones (aldosterone, melatonin, parathyroid hormone, and others) help us maintain body temperature, regulate the amount of urine we produce, adjust to changes in time zones, and monitor the amount of oxygen in our blood. They’re the hormones that control how we function in environments ranging from frozen mountain peaks to sweltering deserts. When they’re out of balance, they can cause bloating, insomnia, fatigue, sweats, and more.
Stress hormones: which include cortisol, epinephrine, and norephinephrine, among others, are produced mainly in the brain and adrenal glands and serve as our body’s alert system. They fire up when something is threatening our health or survival (this includes our need for food and water, temperature stability, and general well-being). When stress hormone levels are briefly elevated, they promote memory formation, motivation, and energy production. When they’re chronically elevated, on the other hand—a situation that’s increasingly common in our fast-paced, multitasking world—they can become toxic and adversely affect our emotional state, memory, and even sleep patterns.
HORMONE EQUILIBRIUM
All these hormones operate in your system like a finely balanced mobile. Just as every part of a mobile is interconnected and shifts when one section moves, each of your hormones is interrelated to the others, and a shift in the level of one will invariably affect the level of another, as well as the overall balance of your system. There’s a constant breeze moving the mobile pieces, too—the environment. (Toxic chemicals in our food, water, and air can disrupt the natural rhythm of our hormones.) When your personal “hormonal mobile” is well balanced, you feel your best and your health flourishes. When the pieces are tilting too much one way or the other, you get symptoms of hormonal imbalance like sexual dysfunction, mood and sleep disorders, and cognitive problems. And when the mobile is severely askew, serious problems, disorders, and diseases are likely to set in.
THE INTRICATE INTERWEAVING OF HORMONES
The sex hormones are in the center of a woman’s hormone mobile because they play the central role in her hormone balance. Aside from their role in reproduction, they provide key functions within each of the other hormone categories. Testosterone, for example, fulfills an energy hormone role by stimulating muscle growth, which helps a woman’s body burn more calories. And when estrogen levels are high, they can promote fluid retention, even though fluid balance is technically a regulatory hormone function. It’s these kinds of crossovers that make sex hormones so powerful and their balance so vitally important. And because these interhormonal relationships are hugely variable and complex, sex hormone imbalances can manifest as symptoms that may appear to have nothing at all to do with the sex hormones themselves. Estrogen, progesterone, and testosterone play multifaceted roles in mood status (anxiety and depression), temperature changes (hot flashes and night sweats), appetite (cravings), sleep (insomnia), and other regulatory functions.
A good example of one abnormal hormone level causing an imbalance with others is polycystic ovarian syndrome (PCOS), a common disorder (it affects at least one in ten reproductive-age women) that’s usually caused by an abnormally high level of the hormone insulin. Typical symptoms of PCOS are weight gain, acne, excess hair growth, and irregular menstrual cycles. The latest evidence suggests that the high insulin levels actually cause the ovaries to produce excessive testosterone. Once the insulin problem is treated, the other hormonal imbalances often self-correct without additional treatment.
Another classic example of hormone interdependence is when one hormone prevents the message of another hormone from getting properly delivered to the brain. This block deprives you of a particular hormone and triggers an imbalance. Too much estrone (the “bad” estrogen), for instance, can block estradiol (the symptom-relieving “good” estrogen) from entering a cell, effectively producing symptoms of estradiol depletion like hot flashes (more about that on page 223ff.). When hormones multitask successfully, all systems run smoothly. It’s only when they fail—when your body has exhausted its ability to increase production of a diminished hormone or convert enough of one hormone into another—that your brain sends you a warning sign in the form of a symptom. Those “whispers” are hormonal messages transmitted by the brain to let you know that you’ve got a hormonal imbalance—and that you should do something about it.
We actually experience minor brain-hormone alerts on a daily basis. Take perspiration, for example. When it’s hot, a reflex initiates perspiration to produce a cooling effect. That in turn results in bodily water loss. Since your health is dependent on maintaining a balance be...
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