Last updated: Mar 02, 2016

The word hormone means to excite—and thats exactly what they do. As chemical messengers, they zip through the blood with a Midas-touch effect, turning up the juice on nearly every receptive tissue they come in contact with.

When a hormone enters one of the 50 trillion or so cells in the body, a cascade of physiological effects is unleashed. Without that moment, a cell may never live up to its full potential, whether its job is to keep your skin supple or help your body process sugar. Over the years, scientists have found roughly 50 different hormones roaming the bloodstream, but these three sex hormones have always run the show for women.

The diva of womens hormones, estrogen spikes at puberty when production soars roughly 20-fold and declines to a herky-jerky trickle at menopause. In between, too little estrogen may send the menstrual cycle on strike (a.k.a. amenorrhea), and too much can make your breasts tender and your brain anxious, irritable, and moody (hello, PMS), according to Susan Lark, MD, author of Hormone Revolution.

In the uterus, an overload of estrogen acts like Miracle-Gro, encouraging the organs lining to go from plush to overgrown, which may invite fibroids and endometriosis. If left to run amok, too much estrogen may harm the very tissues it once nurtured by cranking up cell production, a precursor to cancer of the uterine lining and other cancers.

For most of a womans life, the ovaries make up to 90 percent of her estrogen, but after menopause the 10 percent or so thats left is squeezed out by the adrenal glands and fat tissue.

Because fat cells churn out estrogen, more fat equals more estrogen. In fact, being overweight at menopause (although not recommended) may give you enough estrogen to help fight off osteoporosis and/or delay the need for hormone replacement.

Progesterone is estrogens sidekick. “Its the yang to estrogens yin,” according to Dr. Lark. “Estrogen expands, and progesterone contracts.” So, when estrogen causes fluid retention, progesterone helps the body rid itself of excess water. Where estrogen plumps up the lining of the uterus, the flow of progesterone prunes it.

Aside from keeping estrogen in check, progesterone is a bit of a one-trick pony, and its goal is
to get you pregnant. To that end, a midcycle splash of progesterone triggers a rise in body temperature and ripens up the lining of the uterus so that when an egg comes through it has a nice place to plant itself.

Progesterone production can begin to dip as early as the 30s. When progesterone no longer balances estrogen during perimenopause and menopause, insomnia, brain fog, and anxiety can result.

Associated with beefy muscles and hot tempers, testosterone is found in women as well as men, albeit in much lower levels. Made by the adrenal glands and ovaries, a womans testosterone levels rise and fall each month with a mid-cycle surge. Testosterone imbues women with energy, mental sharpness, and a healthy libido. When testosterone levels drop, so does sex drive.