When most people hear the word testosterone, they immediately think about men, muscle, sex drive, or bodybuilding. That is far too narrow. Testosterone is an important hormone in both men and women, influencing sexual function, body composition, bone and muscle biology, red blood-cell production, and overall physiology. When clinically meaningful deficiency is present, appropriately prescribed testosterone can improve important aspects of health and quality of life.
But I want to make an important distinction from the beginning: Testosterone is not a fountain of youth.
The goal should never be to chase the highest testosterone number possible. The goal is to identify genuine hormonal dysfunction, understand why it exists, and, when treatment is appropriate, restore physiology while protecting the patient’s long-term health. And when we talk about longevity, that distinction matters enormously.
Testosterone Is About More Than Sex
Sexual health matters. It is part of human health. In appropriately diagnosed hypogonadal men, testosterone replacement can improve sexual desire and sexual activity. The Testosterone Trials in older men with low testosterone demonstrated improvements in sexual activity, desire, and erectile function after testosterone treatment.
But testosterone’s biological influence extends beyond the bedroom. One of the areas that interests me most is musculoskeletal health. As we age, we face a relentless challenge: maintaining muscle, strength, power, bone health, balance, and the physical capacity to perform everyday tasks.
Why does that matter? Because longevity without function isn’t the goal. I don’t simply want someone to live to 90. I want them walking at 90. I want them getting out of a chair without assistance. Carrying their groceries. Traveling. Playing with grandchildren. Getting themselves off the floor. Remaining in their own home. Maintaining the physical reserve necessary to recover when illness or injury inevitably occurs. That’s healthspan.
Muscle Is a Longevity Asset
We often talk about muscle as if its only purpose is making us look athletic. Muscle is much more important than that. Skeletal muscle contributes to glucose disposal, metabolic health, mobility, physical reserve and our ability to remain functional as we age. Loss of muscle and strength can contribute to the progression toward frailty and dependence.
This is one reason testosterone deserves attention when genuine deficiency exists. Clinical trials in older men with low testosterone have found increases in muscle strength and power with testosterone administration, although improvements in actual physical function are more variable. In the Testosterone Trials, testosterone produced modest improvements in some mobility measures and self-reported walking ability, but it did not reduce falls. That’s an important lesson. More testosterone does not replace training. Hormone therapy should never become an excuse to avoid resistance exercise, adequate protein, cardiovascular conditioning, sleep, and metabolic health. Testosterone may help create a better physiological environment in an appropriately selected patient. You still have to use that environment.
Testosterone in Men
For men, testosterone deficiency can be associated with decreased libido, reduced spontaneous erections, loss of muscle and strength, changes in body composition, reduced bone mass, anemia and other symptoms. But fatigue, poor motivation, weight gain and reduced sexual function do not automatically mean low testosterone. Sleep apnea, obesity, insulin resistance, medications, alcohol, chronic disease, inadequate sleep, excessive caloric restriction and other factors can produce overlapping symptoms.
Current Endocrine Society guidance emphasizes that male hypogonadism should be diagnosed when compatible symptoms or signs occur together with consistently low, accurately measured testosterone levels, generally confirmed with repeat testing. That’s how I believe testosterone should be approached: Treat the patient, not simply the laboratory number.
Testosterone in Women
Here’s where the conversation gets even more interesting. Women produce testosterone too. But testosterone therapy in women requires considerably more nuance because the evidence and indications are different from those in men.
The strongest international consensus currently supports testosterone therapy for postmenopausal women with hypoactive sexual desire disorder (HSDD) after appropriate biopsychosocial assessment. The evidence demonstrates a moderate beneficial effect on sexual function.
Testosterone is frequently prescribed off-label for women because there is no widely available FDA-approved female testosterone formulation in the United States. We need to be careful not to outrun the science. You’ll hear claims that testosterone in women reliably improves energy, cognition, mood, muscle, body composition, bone health and longevity. Some of these possibilities are biologically interesting and plausible, and we have seen it. But keep in mind studies as a general rule in women have been lacking for years.
That means we keep asking questions. It means we distinguish between what we know, what we suspect, and what still needs to be proven. That’s responsible longevity medicine.
Testosterone and Independent Living
This may be the part of the testosterone conversation that gets overlooked most. Imagine two 80-year-olds.
Both are alive. One walks independently, strength trains, travels, cooks, drives, climbs stairs, carries groceries and plays with grandchildren. The other requires assistance getting out of a chair, has lost substantial muscle and strength, fears falling, and can no longer safely live independently. Chronologically, they’re the same age.
Functionally, they’re living in completely different worlds. That’s why I believe one of the most important questions in longevity medicine is: What are we doing today to preserve tomorrow’s independence?
Hormonal health can be one component of that strategy, particularly when a genuine deficiency is compromising muscle, bone, sexual health or well-being. But testosterone isn’t the strategy by itself.
Strength is the strategy.
The Testosterone–Muscle–Independence Connection. Think about aging as a battle to preserve physiological reserve.
We want to maintain: Muscle → strength → power → mobility → independence.
Those aren’t identical things, but they’re connected. You need enough muscle to generate force. You need strength and power to perform real-world activities. You need mobility to continue interacting with your environment. And maintaining those capacities increases your opportunity to remain independent.
That’s why I would never prescribe testosterone and tell someone, “You’re optimized.”
The prescription is only one piece. Lift weights. Eat sufficient protein. Walk. Train cardiovascular fitness.
Protect your sleep. Maintain metabolic health. Keep your body composition healthy. Then, when clinically indicated, optimize hormonal physiology alongside those foundations.
Does Testosterone Make You Live Longer?
This is where the longevity industry needs to be careful. We do not currently have evidence showing that testosterone replacement itself extends human lifespan. That claim goes beyond the data. What we can reasonably discuss is whether correcting clinically significant testosterone deficiency may improve particular health outcomes and quality-of-life domains that matter during aging. Those are different statements.
The objective isn’t: Testosterone → immortality.
It’s: Appropriate hormonal health + muscle + strength + metabolic health + cardiovascular fitness + sleep + nutrition + purpose → greater opportunity for a longer healthspan.
That’s a much more defensible, and much more powerful, longevity model.
Testosterone Isn’t Risk-Free
Any discussion of benefits without discussing risk isn’t medicine. In men, testosterone can increase hematocrit and suppress spermatogenesis, so men wishing to preserve fertility need a different conversation. Monitoring may include testosterone levels, CBC/hematocrit, symptoms, prostate assessment when appropriate, and evaluation of cardiometabolic factors.
Current guidance also identifies situations in which testosterone should not be initiated without further evaluation or is contraindicated, including elevated hematocrit and certain prostate, cardiovascular, sleep-apnea, fertility, and thrombotic circumstances.
The cardiovascular discussion has evolved as well. The large TRAVERSE program was reassuring regarding major heart attack and stroke outcomes over its follow-up period, but that does not mean testosterone is risk-free. The Endocrine Society’s 2026 statement continues to emphasize individualized diagnosis, risk-benefit assessment and monitoring.
Women require different dosing and monitoring. Excessive androgen exposure can cause acne, increased facial/body hair, scalp hair loss, voice changes and other androgenic effects. Therapy should aim to maintain concentrations within an appropriate physiologic female range rather than producing male-range testosterone levels.
Don’t Optimize a Hormone While Ignoring the Human
This is one of my biggest concerns with modern hormone medicine. Someone gets a testosterone result.
The number becomes the diagnosis. The prescription becomes the solution. And nobody asks why. For a man with obesity, poor sleep and insulin resistance, improving metabolic health and losing excess body fat may improve testosterone physiology. The Endocrine Society specifically notes weight loss as first-line therapy for appropriately diagnosed hypogonadism associated with overweight or obesity when another cause isn’t identified.
Similarly, in women we should consider menopause status, estrogen status, thyroid function, medications, sleep, stress, relationship factors and other contributors to sexual symptoms before assuming testosterone is the answer. Hormones work as a system. So should medicine.
Authentic Longevity Means Maintaining Capacity
My definition of longevity isn’t seeing how long we can keep a heartbeat going. I want capacity.
- The capacity to move.
- The capacity to think.
- The capacity to work.
- The capacity to serve.
- The capacity to travel.
- The capacity to love.
- The capacity to remain independent.
- And ultimately, the capacity to fulfill your purpose.
That’s why muscle, hormones, metabolic health, cardiovascular fitness, cognition, relationships, faith and purpose all belong in the longevity conversation. Testosterone can be an extraordinarily useful therapeutic tool when the right patient receives the right treatment for the right reason and is appropriately monitored. But don’t confuse optimization with maximization. The goal isn’t to create the highest testosterone level. The goal is to create the healthiest human being. And perhaps the greatest measure of successful longevity isn’t the number of candles on your birthday cake. It’s whether you’re still strong enough to carry the cake to the table yourself.
To hear more from Dr. Mark Sherwood on what actually affects your testosterone levels, how to know if your testosterone is low, which blood tests matter, and what you should know before considering testosterone therapy and more, watch the full episode of The Authentic Longevity Podcast on YouTube here: Testosterone Replacement Therapy (TRT): What You Need to Know
About Drs. Mark and Michele Sherwood
Dr. Mark Sherwood, ND, is a traditional naturopathic doctor and clinician, and Dr. Michele Sherwood, DO, is a physician. Together, they are educators, authors, speakers and co-founders of the Functional Medical Institute in Tulsa, Oklahoma. Their work focuses on personalized, whole-person health with an emphasis on prevention, metabolic health, healthy aging, performance and longevity.
Their new book, Authentic Longevity: Unlocking Lifelong Vitality, The Sherwood Way, combines decades of clinical experience, patient stories and actionable science to explore nutrition, movement, sleep, stress and hydration alongside genetics, peptides, supplements, hormones, laboratory testing and the role of emotional and spiritual health in healthy aging.
