S1E30 Hormones 101: What They Are, How They Work & Why They Matter After 40

What if the fatigue, weight changes, brain fog, poor sleep, anxiety, low libido, or changes in your workouts aren't simply signs of getting older? In this solo episode of 40s Forward, Dr. Betsy Greenleaf goes back to the basics with Hormones 101—a foundational guide to what hormones actually are, how they communicate throughout the body, and why understanding them becomes increasingly important after 40. This episode kicks off a deeper hormone series exploring estrogen, progesterone, testosterone, thyroid hormones, cortisol, insulin, DHEA, oxytocin, growth hormone, and more. What You'll Learn in This Episode • What hormones actually are and how they communicate with your cells • Where hormones are produced throughout the body • How hormonal feedback loops maintain balance • Why hormones affect much more than reproduction • How hormones influence mood, memory, metabolism, sleep, skin, bones, and libido • Why hormonal changes often become noticeable after 40 • The roles of estrogen, testosterone, progesterone, and thyroid hormones • Why hormones never work independently • How stress, nutrition, sleep, inflammation, the microbiome, and genetics interact with hormones • Why hormone therapy should be individualized What Are Hormones? Think of your body as an enormous company with trillions of employees. Your cells perform different jobs, but they need a way to communicate. Hormones are those messengers. Produced throughout the body, hormones travel through the bloodstream carrying instructions that influence growth, repair, metabolism, blood sugar, bone health, sleep, hunger, mood, sexual desire, reproduction, and much more. Hormones don't do the work themselves—they tell your cells what to do. Your Body Is an Endocrine Network Hormones don't come only from the ovaries or testes. The brain, pituitary, hypothalamus, thyroid, adrenal glands, pancreas, ovaries, testes, fat tissue, intestines, kidneys, heart, bones, and muscles all participate in this sophisticated communication network. Dr. Greenleaf explains hormonal feedback loops using the analogy of a thermostat: the body constantly senses what it needs and adjusts its signals to maintain balance, or homeostasis. Hormones Are Life Hormones Estrogen isn't just about periods and reproduction. Testosterone isn't just about muscle and sex drive. Progesterone isn't only about pregnancy. These hormones influence the brain, bones, cardiovascular system, metabolism, immune function, mood, energy, sleep, skin, pelvic health, and more. Thyroid hormones also play an essential role in metabolism, temperature regulation, heart rate, digestion, hair, skin, nails, brain function, and energy production. Why Everything Can Feel Different After 40 Hormones rarely disappear overnight. They fluctuate and change over time. That may show up as: • Fatigue • Weight gain • Anxiety or mood changes • Brain fog or memory changes • Aching joints • Low motivation • Lower sex drive • Sleep disruption • Skin changes • Workouts that suddenly don't seem to work These symptoms aren't always caused by hormones—but hormones interact with nearly every system involved. Don't Chase Hormones—Chase Physiology One of Dr. Greenleaf's most important messages is that hormone optimization is about more than simply replacing a number on a lab test. Nutrition, sleep, stress, movement, genetics, inflammation, environmental exposures, medications, trauma, and the microbiome can all influence how your body produces, processes, and responds to hormones. That's why hormone therapy isn't one-size-fits-all. Do You Need Hormone Replacement Therapy? Hormones can be a valuable tool, but Dr. Greenleaf emphasizes individualized decision-making. Whether to start hormone therapy, continue it, or eventually stop should involve an informed conversation about your symptoms, health, risks, goals, and quality of life—not a blanket recommendation that everyone should or shouldn't take hormones. Key Takeaways • Hormones are chemical messengers affecting nearly every body system • Hormonal health is about much more than reproduction • Estrogen, progesterone, testosterone, and thyroid hormones have widespread effects • Hormonal changes can contribute to symptoms after 40 • Hormones interact with sleep, stress, nutrition, inflammation, and the microbiome • Hormone therapy should be personalized • Understanding your hormones can help you better understand your body Who This Episode Is For • Women and men over 40 noticing changes in how they feel • Anyone navigating perimenopause, menopause, or andropause • People experiencing fatigue