Low testosterone (low T) affects approximately 40% of men over age 45, according to research. While testosterone naturally declines with age — typically about 1-2% as you reach the age of 40 — significant drops can impact your physical health, mental well-being, and quality of life.
Recognizing the signs early is crucial. In this guide, we'll explore the key indicators of low testosterone, share evidence-based insights from leading endocrinology research, and provide actionable steps if you're experiencing symptoms.
What Is Testosterone?
Testosterone is the primary male sex hormone (androgen) produced mainly in the testicles, with smaller amounts synthesized in the adrenal glands. While often associated exclusively with male characteristics, testosterone plays critical roles throughout the body that extend far beyond reproduction.
Testosterone plays a central role in:
- Sexual function & fertility: Supports libido, erections, and sperm production.
- Muscle mass & strength: Promotes protein synthesis and helps maintain lean muscle.
- Bone density: Helps keep bones strong and reduces the risk of osteoporosis and fractures.
- Body fat & metabolism: Influences where you store fat and how your body uses energy; low levels are linked with higher rates of obesity and metabolic syndrome.
- Mood & cognition: Impacts motivation, confidence, mood, and cognitive functions like focus and memory.
How Testosterone Levels Change With Age
Normal total testosterone levels for adult men typically range from 300 to 1,000 ng/dL (nanograms per deciliter). Levels below 300 ng/dL are generally considered low and may warrant treatment, though symptoms matter more than numbers alone. Lifestyle factors (like excess body fat, poor sleep, and chronic illness) can also lower testosterone at any age.
Age-Related Decline:
- Peak Production: Late teens to early 20s
- Annual Decline: 1-2% per year after age 40
- By Age 60: Many men experience a 30-40% reduction from peak levels
Common Signs and Symptoms of Low Testosterone
Low testosterone manifests differently in every man, and symptoms often develop gradually over months or years. According to a 2020 study in The Aging Male, men frequently dismiss early symptoms as "normal aging" until multiple symptoms compound and significantly impact quality of life. Recognizing the signs of low testosterone can help you take action early. Here are some common symptoms to look for:
- Fatigue and Low Energy: Persistent tiredness that doesn’t improve with rest or reduced stamina during physical activity or workouts.
- Mood Changes: Increased irritability or mood swings, symptoms of depression or anxiety that weren’t present before.
- Body Composition Changes: Unexplained weight gain, particularly around the abdomen, loss of muscle mass and strength, even with regular exercise.
- Sleep Disturbances: Difficulty falling asleep or staying asleep, experiencing insomnia or other sleep-related issues.
- Decreased Libido: Decreased sex drive, erectile dysfunction, infertility, low or zero sperm count.
- Cognitive Changes: Difficulty concentrating or frequent memory lapses, brain fog that affects daily activities.
Important: These symptoms are nonspecific—they can be caused by many things (stress, poor sleep, other medical conditions). But when several of them show up together, it’s worth checking your testosterone levels instead of just pushing through.
Evidence-Based Insights on Low Testosterone
Low testosterone is more common than most men realize. Large population studies suggest that a significant percentage of men over 45 have total testosterone levels below the typical lab reference range, and the likelihood increases with age, higher body fat, and chronic conditions like type 2 diabetes and metabolic syndrome. In other words, low T isn’t rare — it’s just often missed or written off as “normal aging.”
Research shows that low testosterone is closely linked with metabolic and cardiovascular health. Men with low T are more likely to carry excess abdominal fat, have insulin resistance, and develop metabolic syndrome, all of which increase the risk for type 2 diabetes and heart disease. Several observational studies have found that lower testosterone levels are associated with higher rates of cardiovascular events and overall mortality, even when adjusting for other risk factors.
Bone health is another big piece of the picture. Testosterone helps maintain bone density, and chronically low levels can contribute to osteopenia, osteoporosis, and a higher risk of fractures later in life. For many men, low T isn’t just about energy or sex drive — it’s part of a broader shift in body composition, strength, and long-term resilience.
At the same time, the conversation around TRT is evolving. Historically, concerns about cardiovascular risk and prostate health led to very conservative FDA labeling and a lot of confusion for patients and clinicians. More recent data from large, well-designed trials have helped clarify the risk profile of TRT in appropriately selected men—and even prompted the FDA to update its labeling language. If you want a deeper look at how regulators and experts are rethinking TRT safety, our blog Inside the FDA Expert Panel on Testosterone Replacement Therapy breaks down the key takeaways in detail.
At Thrive, we look at low testosterone as a signal about your overall health, not just a single lab number to “fix.” That’s why our providers combine comprehensive lab work with your symptoms, lifestyle, and goals before recommending any treatment plan.
Final Thoughts
If you’ve been nodding along to several of these symptoms, the next step isn’t to panic—it’s to get curious and get data. Start by scheduling an appointment with your healthcare provider to discuss your concerns and request a test to check your testosterone levels.
While awaiting results or pursuing treatment, focus on lifestyle factors that support healthy hormone levels: work with a personal trainer to establish a strength training routine, consult a registered dietitian for guidance on a balanced diet rich in healthy fats and proteins, prioritize 7-9 hours of quality sleep, and practice stress management techniques like meditation or yoga. If diagnosed with low testosterone, discuss treatment options with your provider, including testosterone replacement therapy (TRT) and other evidence-based interventions.
Remember, low testosterone is a common and treatable condition—you're not alone on this journey. With the right support and treatment plan, you can start feeling like yourself again. Have questions about hormone health or wellness optimization? Schedule a consultation with a Thrive Advisor to explore personalized solutions for your health goals.
This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.
