Long-Term Evidence and Research on Hormone Therapy

Hormone therapy, also known as Hormone Replacement Therapy (HRT), remains one of the most studied areas in anti-aging and longevity medicine. The evidence base, particularly for testosterone and HGH replacement, has evolved substantially over the past decade, clarifying who benefits, how benefits are delivered, and if and where genuine risks are relevant.

For women, contemporary menopause society guidance affirms that HRT is still the most effective therapy for troublesome menopausal symptoms such as night sweats and hot flashes. Current clinical research affirms that HRT for women prevents bone loss and can minimize fractures. As to other benefits, a recent study concluded that “transdermal estradiol and lower doses are associated with lower thromboembolic and stroke risk than oral preparations, especially when initiated in healthy women under 60 or within 10 years of menopause onset.”

For men with clinically confirmed hypogonadism (low testosterone), the 2023 TRAVERSE trial reported no excess in major adverse cardiovascular events over 2 years with appropriately indicated testosterone therapy, helping resolve a decade of safety controversy. In 2025, the U.S. FDA removed boxed-warning language about increased cardiovascular risk from all testosterone products.

Finally, in adults with growth hormone deficiency (AGHD), many studies and recent reviews support favorable safety and improvements in body composition, lipids, and quality of life when HGH therapy is titrated and monitored.

Evidence for the Safety and Efficacy of HRT for Women

The North American Menopause Society, more recently known as “The Menopause Society,” confirms that systemic HRT is the most effective treatment for vasomotor symptoms and sexual health issues, and prevents bone loss in women approaching and in menopause. These same studies have determined that “benefit–risk” is most favorable when HRT is started before the age of 60, or within 10 years of menopause.

Much of the reporting you may be familiar with regarding the “dangers” of HRT for women came from a 30-year-old, since discredited study known as the Women’s Health Initiative or WHI. Now, Decades later in 2024, the NIH’s recent reanalysis of the WHI finds that age, type of HRT, and medical history are the key factors in determining risk, and with proper medical supervision, HRT is safe for most women.

What Does the Latest Research Say About Testosterone Replacement Therapy?

Evidence for the Safety and Efficacy of Hormone Therapy for Men

Endocrine Society guidance recommends testosterone therapy (TRT) only for men with clinical symptoms who have been tested and diagnosed with low testosterone.

Recently, researchers from the prestigious Perelman School of Medicine at the University of Pennsylvania, in association with a dozen other well-respected medical centers nationwide, conducted seven clinical trials in partnership with the National Institute on Aging to determine the value of testosterone replacement therapy for aging men.

A recent landmark collective study known as the “Testosterone Trials” (TTrials) concluded that “The trials showed an improvement in all the aspects of sexual function and overall mood.”

The TTrials were a coordinated set of seven placebo-controlled, double-blind trials in 788 men with a mean age of 72 years, designed to determine the efficacy of increasing the testosterone levels of older men with low testosterone through the use of testosterone replacement therapies.

The findings of the Testosterone Trials were published in March 2018. The key takeaways from the TTrials were that for older men with low testosterone, testosterone treatment for one year:

• Improved all aspects of sexual function
• Improved strength and mobility
• Improved mood and depressive symptoms
• Markedly increased bone mineral density and estimated bone strength.

In addition to the TTrials, there have been numerous studies that have shown the many positive benefits of testosterone replacement therapy for men suffering from andropause. For example:

A 2011 study on when to expect to see results from testosterone therapy found, “Effects on sexual interest appear after three weeks, plateauing at six weeks, with no further increments expected beyond. Changes in erections/ejaculations may require up to 6 months. Effects on quality of life manifest within 3–4 weeks, but maximum benefits take longer. Effects on depressive mood become detectable after 3–6 weeks with a maximum after 18–30 weeks.”

According to the study, published in the January 2015 edition of Mayo Clinic Proceedings, “evidence from research conducted around the world for several decades suggests a beneficial relationship between [testosterone] therapy and cardiovascular health.”

A 2009 study concluded that “Restoring testosterone levels to within the normal range by using testosterone replacement therapy can improve many of the effects of hypogonadism. Most importantly, these include beneficial effects on mood, energy levels, and patients’ sense of well-being, sexual function, lean body mass and muscle strength, erythropoiesis and bone mineral density (BMD), cognition, and some benefits on cardiovascular risk factors.”

What Does the Latest Research Say About Growth Hormone Therapy?

HGH therapy has been just as extensively studied as testosterone replacement. The National Institutes of Health has recently provided the Ohio University Edison Biotechnology Institute and Heritage College of Osteopathic Medicine with $2.23 million to John Kopchick, Ph.D., to follow up on his earlier work that found that growth hormone could extend the lifespan of mice.

A study entitled Obesity, growth hormone, and weight loss, concluded that growth hormone could indeed reduce abdominal fat.

Another found that HGH specifically reduced obesity in post-menopausal women. And yet another on HGH and weight loss in children confirmed that “HGH had [fat burning] properties that resulted in reduction and redistribution of body fat.”

A study on HGH published in the March 2018 edition of the International Journal of Molecule Science, entitled, Treatment with Growth Hormone for Adults with Growth Hormone Deficiency Syndrome: Benefits and Risks concluded: “Growth hormone replacement exerts unquestionable beneficial effects in many [adult] patients with GHD, and its use is safe for approved indications. [In addition,] HGH has shown beneficial effects on body composition, exercise capacity, bone structure, serum lipids, and quality of life.”

Research indicates that there is a definitive link between arousal, HGH, and sexual function. Studies have found that upon sexual excitement, HGH levels also increase. The same studies found that men with ED had as much as seven times less HGH in their erectile tissues when non-erect than in men with normal erectile function. One such study published in 2000 concluded, “[Our] results suggest that penile erection is probably induced by growth hormone through its stimulating activity on human corpus cavernosum smooth muscle.”

TRT vs. HGH — Evidence Snapshot

Benefit	TRT — Evidence for Benefit?	TRT — Ongoing Research?	HGH — Evidence for Benefit?	HGH — Ongoing Research?	Clinical Context
Anti‑Aging	Moderate	Yes	Moderate	Yes	Neither TRT nor HGH is indicated purely for anti‑aging in otherwise healthy adults, but each provides several benefits that improve overall health and could increase longevity.
Weight Loss / Body Composition	Yes	Yes	Yes	Yes	TRT (in hypogonadal men) and GH (in AGHD) improve body composition; weight loss is modest and context‑dependent.
Sexual Health (Libido/Erectile Function)	Yes	Yes	Yes	Yes	Both TRT and HGH improve sexual function in men and women with lower-than-normal levels of either hormone.
Cognitive Benefits	Yes	Yes	Yes	Yes	There is significant clinical evidence for improvements in memory and cognition of both therapies.
Heart Health / Cardiovascular Outcomes	Moderate	Yes	Moderate	Yes	While not prescribed to treat any specific heart condition, there is clinical evidence that the effects on circulation and metabolism of both therapies can improve heart health.

Notes:

• “Evidence for Benefit?” reflects current, generalizable clinical evidence for indicated populations (e.g., TRT for confirmed hypogonadism; GH for adult growth hormone deficiency).
• “Ongoing Research?” flags active study areas; findings may evolve.
• This table intentionally omits study citations; see the main article for references.

Clinical Studies on the Long-Term Benefits and Effects of HRT

Across position statements and large meta-analyses, long-term advantages include durable relief of vasomotor symptoms and fracture prevention via bone mass preservation. Absolute risks for thromboembolism and certain cancers vary by age, time from menopause, route, and progestogen choice—with transdermal estradiol and micronized progesterone often favored for lower risks.

In men, research indicates that long-term outcomes hinge on appropriate diagnosis, monitoring, and individualized treatment. With that prerequisite, the aforementioned TTrials provide significant support for the long-term benefits of TRT.

As to the long-term effects of HGH therapy, in men diagnosed with AGHD, many peer-reviewed studies support long-term safety and benefits of HGH for body composition, sexual health, cognition, and overall quality of life.

Clinical Studies on the Anti-Aging Benefits of Hormone Therapy

Though never responsibly prescribed strictly to slow or reverse aging in patients who are not hormone-deficient, there is significant evidence for the “anti-aging” benefits of HRT. Before diving into these proven capabilities, let’s clarify exactly what “anti-aging” means.

Anti-aging medicine focuses on reducing the risks of aging-related diseases and improving overall health by addressing the biological aging process through lifestyle interventions and scientifically supported therapies like hormone replacement.

The American Academy of Anti-Aging Medicine (A4M) is a leading advocate for anti-aging practices. Dr. Ronald Klatz, co-founder of A4M and author of Grow Young with HGH, states, “The anti-aging effects of hormones like HGH and testosterone impact the body holistically—mentally and physically, structurally and functionally. By restoring hormone levels, individuals can reclaim their vitality, health, appearance, and sexual wellness.”

HGH and testosterone are crucial hormones vital for maintaining optimal health. Unfortunately, levels of these hormones decline naturally with age. Symptoms commonly associated with aging—such as fatigue, weight gain, decreased libido, cognitive decline, and diminished muscle mass—are directly related to falling levels of HGH and testosterone.

Clinicians have long recognized that replenishing these hormones can reverse many signs of aging. Pioneering studies, including the landmark 1990 research by Dr. Daniel Rudman published in the New England Journal of Medicine, confirmed significant anti-aging effects in participants receiving HGH treatment, such as increased muscle tone, fat reduction, improved skin elasticity, and enhanced general well-being. Similarly, numerous studies, as mentioned on these pages, validate testosterone replacement therapy’s ability to boost vitality, muscle mass, cognitive functions, and sexual health.

What Makes Medzone Different: The Advantages of Evidence-Based HRT

At Medzone, we practice evidence-based, precision hormone care. That means we diagnose first, treating only legitimate medical conditions such as menopause, low testosterone, or age-related growth hormone deficiency. We then precisely match the formulation and route to the patient, based on the kinds of studies and clinical evidence cited in this article.

Every one of our HRT patients is carefully monitored under strict medical supervision, and doses are adjusted as needed to maximize effectiveness and minimize side effects. We also make sure that our staff and doctors stay up to date as new research on HRT emerges. This is how we translate world-class evidence into personalized results—safely.

If you are ready to see what evidence-based HRT can do to improve your quality of life, contact us today!

Frequently Asked Questions about HRT and HRT Research

1. What exactly is Hormone Replacement Therapy (HRT)?

Hormone Replacement Therapy is a medical treatment that helps restore hormones that naturally decline with age. For women, it often means estrogen and progesterone to relieve menopausal symptoms. For men, it may involve testosterone replacement to address low-T. The goal is to restore balance, relieve symptoms, and improve quality of life under medical supervision.

2. Is hormone therapy only for people with severe symptoms?

No. HRT can benefit anyone experiencing noticeable symptoms of hormone imbalance—such as fatigue, hot flashes, mood swings, low libido, or poor sleep. Early evaluation helps tailor a plan before symptoms become more disruptive or lead to other health issues like bone loss or muscle decline.

3. Has hormone therapy become safer over the years?

Yes. Today’s hormone therapies are safer than ever thanks to improved formulations, personalized dosing, and ongoing medical research. Modern approaches use bioidentical hormones and modern delivery methods that lower certain risks compared with older therapies.

4. How long does it take to feel results from hormone therapy?

Most patients begin noticing improvements in energy, mood, and sleep within a few weeks, while changes in body composition, skin tone, or libido may take several months. Consistent monitoring ensures the right dose adjustments for steady, safe progress.

5. Is there ongoing research into hormone therapy?

Absolutely. New studies are constantly evaluating long-term outcomes, safer delivery systems, and the broader benefits of HRT for heart, bone, cognitive, and metabolic health. Medzone’s protocols are continuously updated to reflect the most reliable clinical findings.

6. Can natural supplements or lifestyle changes replace hormone therapy?

While diet, exercise, stress reduction, and certain herbal supplements may support hormonal balance, they cannot fully replace prescription HRT when hormone levels are clinically low. These approaches are best used as complements to medical therapy, not substitutes.