You might remember hormones from your sex-crazed teen years. Or your partner's most recent crying jag. But if you're sitting there smugly thinking that you're immune from hormonal chaos just because you're (a) no longer a teenager and (b) male, think again. In fact, if you knew all the ways hormones could mess up your life, you'd probably start crying like a little girl. Off-kilter hormone distribution can make you store too much fat, hamper your ability to fight stress, and cause you to eat when you're full. It can lead to metabolic syndrome and diabetes and can adversely affect your sleep and sex life.
That's a lot that can go wrong. This is due to the vast reach of your endocrine system, which commands body activity utilizing powerful hormones. "It's like your body's internal Internet," says pharmacologist John McLachlan, Ph.D., director of the center for bioenvironmental research at Tulane University. "Your hypothalamus and pituitary glands are the control centers, like servers sending out messages going back and forth among your organs. Your pancreas, adrenal glands, thyroid, and testes are all part of this finely tuned system."
That fine-tuning increases the system's vulnerability, as it relies on complex feedback to regulate itself. "If that feedback is distorted, it can disrupt the process," says Vivian Fonseca, M.D., chief of endocrinology at Tulane University's health sciences center.
Use our guide to ensure your hormones are doing their jobs.
Stress hormones: Cortisol and epinephrine
Whether you're fending off an angry rottweiler or an angry client, your body's response to stress is the same: Your hypothalamus floods your blood with hormones to frighten you into action. "Cortisol and epinephrine are your body's alarm-system hormones," says Dr. Fonseca. They make your heart beat faster and dilate your bronchial tubes so they can feed oxygen to your brain and keep you alert. They also release fat and glucose into your bloodstream to provide emergency energy.
Are your hormones in tune?
Too much stress can keep your cortisol levels consistently elevated, which disrupts your metabolic system. This, in turn, signals your cells to store as much fat as possible. Worse, the fat tends to accumulate in your belly as visceral fat, which resides behind your abdominal muscles and has more cortisol receptors than other fat does.
To defend yourself against stress-hormone disruption, make a habit of exercising for an hour a day, 3 days a week. Doing so helps regulate your cortisol levels, say researchers at Ohio State University. Also try to eat organic foods as much as possible in order to steer clear of the common pesticide atrazine. This chemical has been shown to affect hormonal balances in amphibians, reptiles, birds, and mammals. A National Health and Environmental Effects Research Laboratory study showed that atrazine produced extreme increases in stress-hormone levels in rats. In fact, the stress reaction was similar to that seen when the animals were restrained against their will, the study noted.
Weight hormones: Leptin, ghrelin, CCK, insulin
You have an army of hormones telling you when to eat and when to put the fork down. The hormone ghrelin begins the cycle when your stomach is empty by prompting neurons in your hypothalamus to make you feel hungry. Then when you start eating, your stomach stretches and you secrete cholecystokinin (CCK), an appetite suppressant.
Hormones now begin working overtime to help you back away from the table. Your intestines produce peptide YY, which tells your brain you've had enough to eat, and your pancreas sends out insulin. This signals that you're metabolizing a meal and that you shouldn't consume any more. Leptin, a hormone produced by fat cells, also tells your hypothalamus that you're full by prompting the secretion of alpha-MSH, which is another appetite-suppressing hormone.
All this helps your body maintain a balance between hunger and satiation. Why so many hormones in the game? "Energy regulation is necessary for survival, so we have many redundant pathways in case any fail," says Robert Lustig, M.D., an endocrinologist at the University of California at San Francisco. "But we were never supposed to have so much food so readily available, and certainly not this much sugar."
Are your hormones in tune?
Hungry? Full? You may not be able to trust your gut. When you put on extra weight, you start secreting excess leptin. "And if you secrete a lot of leptin on a chronic basis, it should tell your brain, 'Look, you're putting on weight; you need to cut back,'" says Dr. Fonseca. But disruptions in leptin (mostly from too much sugar) instead tell your brain to send out hunger signals, even if you've just eaten. This can lead to fatty liver disease and insulin resistance. "When your insulin goes up, it blocks leptin signaling, which means your brain thinks you're starving," Dr. Lustig says. This, of course, sets up a wicked feedback cycle as you pack on the pounds.
Beyond losing weight, your best defense against leptin disruption is to reduce your sugar intake. Americans consume an average of 22 teaspoons of sugar a day; the American Heart Association recommends that men eat no more than 9. And it's not just high-fructose corn syrup that you need to avoid; table sugar and fruit juice can be as bad as soda. In fact, 100 percent fruit juice has 1.8 grams of fructose per ounce, while soda has 1.7 grams per ounce, Dr. Lustig notes.
Sex hormones: Testosterone, LH, FSH
That rock-hard erection you're so proud of? Thank your hormones—specifically, testosterone, the key ingredient for normal sexual health in men. Its production is prompted by something called luteinizing hormone (LH), while the follicle-stimulating hormone (FSH) helps produce the actual sperm. When you're aroused, your adrenal glands pump out epinephrine and norepinephrine, raising your heart rate and moving blood into your muscles, brain, and penis. Then the hormone dopamine increases your sexual appetite and communicates with the hypothalamus to orchestrate your erections.
Are your hormones in tune?
Elevated estrogen levels can eclipse your testosterone, zapping sex drive. Yes, men have estrogen too. "In fact, the most widely spread hormone receptor in the body is the estrogen receptor," says McLachlan. When a man is exposed to estrogenic chemicals—such as bisphenol A (BPA), the endocrine disruptor found in plastics and food-can linings—he can experience erectile dysfunction and weight gain. (Follow these nine rules for stronger erections.)
Your best defense against an estrogen invasion is to lose weight and build muscle. "Fat converts your testosterone to estrogen," says Jack Mydlo, M.D., chairman of the department of urology at Temple University school of medicine. Dropping pounds will improve your testosterone-to-estrogen ratio, which improves your sex drive as well as your erections. And when you're actively building muscle, you become more sensitive to insulin, which means you can push more glucose into the muscle, says Dr. Fonseca. This produces more fat-burning, libido-boosting energy.
Energy hormone: Thyroxine
Your thyroid gland controls your metabolism, which is your body's mechanism for turning calories into energy. It's yet another chain of command: Your hypothalamus detects fatigue and then your pituitary gland signals your thyroid to secrete thyroxine. This hormone enters almost every cell in your body. "It boosts sugar burning and oxygen intake in cells," says McLachlan. "This raises your body temperature and increases your heart rate." (Before you load up on caffeine, learn the truth about energy drinks.)
Are your hormones in tune?
When this system is out of whack, the result can be muscle breakdown, weakness, fatigue, and weight gain. While most thyroxine disruptions are genetic, there is growing evidence that some environmental compounds can block thyroxine, says McLachlan. A 2009 study suggests that BPA can displace thyroxine from its receptor and block it. Brominated flame retardants (BFRs) and polychlorinated biphenyls (PCBs) also both interfere with your thyroid. (BFRs are found in clothes, furniture, and electronics; PCBs, which are no longer in use in the United States, can still be found in the environment, particularly in farmed salmon.) "If you're exposed to these, you could end up with a form of hypothyroidism—an underproduction of thyroxine that causes low energy and weight gain," says McLachlan. On the other end of the spectrum, hyperthyroidism, or overproduction of thyroxine, can cause anxiety, increased heart rate, weight loss, an enlarged thyroid, and swelling behind the eyes. Your doctor will be able to identify thyroid problems by prescribing a thyroid-stimulating hormone (TSH) blood test; fixes for both may include surgery or dietary changes, as well as lifelong daily doses of prescription drugs.
Sleep hormone: Melatonin
When the sun goes down, your pineal gland switches on like clockwork to secrete melatonin, a hormone that helps you fall asleep and regulates your circadian rhythm. It lowers your core body temperature, which if too high promotes wakefulness. Production of melatonin peaks in the middle of the night, and the process can be disrupted by even very low levels of artificial light.
Are your hormones in tune?
Mounting evidence suggests that exposure to light at night—whether you're asleep or awake—might play a crucial role in cancer, diabetes, and obesity. The World Health Organization classified "circadian disruption" as probably carcinogenic, and light at night is considered by some to be an endocrine disruptor that may affect melatonin, cortisol, ghrelin, leptin, and testosterone. "Most people think, and the drug companies want you to think, that waking up at night is bad for you," says Richard Stevens, Ph.D., a cancer epidemiologist at the University of Connecticut health center. But that's not the case, he says—it's exposure to light at night that's the problem. "If you wake up at night, as most of us do, that is a period of quiet wakefulness—stay in bed, in the dark, and enjoy it," Stevens suggests.
You don't have to be asleep to have good melatonin rhythm, but you do need to be in the dark. Buy heavy curtains, cover your alarm clock, and turn off gadgets. "Make it dark enough that you can't see your hand," Stevens says. "If you go to the bathroom and turn on that bright light, you'll lower melatonin almost immediately," says Stevens. "I actually have a red night-light in my bathroom, because red light has less effect on melatonin than white or blue light," he says.