Testosterone Replacement Therapy After 40:
What Changes and What to Watch For
For many men, their early 40s are when things start to feel different.
Energy isn’t what it used to be. Recovery takes longer. Muscle is harder to maintain, while fat gain seems easier. Libido, motivation, and mental clarity may decline, even when diet and exercise haven’t changed much.
This is often when testosterone replacement therapy (TRT) comes up. But determining whether TRT is appropriate requires more than a single lab value.
What Actually Changes After 40
Testosterone levels naturally decline with age, typically beginning in the late 30s or early 40s. For some men, this decline is subtle. For others, symptoms can meaningfully affect daily life and performance.
Common symptoms associated with low or declining testosterone include:
• Reduced muscle mass and strength
• Increased body fat
• Low energy or motivation
• Poor workout recovery
• Decreased libido
• Mood or focus changes
But it’s important to know that testosterone does not exist in a vacuum. Sleep, stress, nutrition, exercise habits, alcohol intake, and metabolic health all influence how testosterone functions in the body.
When “Normal” Testosterone Levels Don’t Tell the Full Story
One of the most common frustrations men experience is being told their testosterone is “in range,” despite feeling anything but optimal.
However, lab reference ranges are broad. A value that is technically normal may still be suboptimal for a specific individual, especially when symptoms are present and persistent.
TRT decisions should not be based solely on numbers. They should be based on:
• Symptoms and quality of life
• Trends in lab values over time
• Body composition and metabolic health
• Training capacity and recovery
• Sleep, stress, and nutrition
In this context, TRT is not about chasing a number. It’s about optimizing function and treating the patient as a whole.
When TRT Might Make Sense
TRT may be appropriate for men who are experiencing symptoms that are consistent with testosterone deficiency, especially when these symptoms are supported by lab values and a thorough clinical evaluation. It's also important that lifestyle factors are being addressed or actively improved.
When used appropriately, TRT can improve lean muscle mass and strength, boost energy and mood, enhance exercise tolerance and recovery, and support libido and sexual function. However, it's important to remember that TRT is meant to support healthy lifestyle habits, not replace them.
Before you start, make sure you have a clear discussion of the potential risks and benefits with your health provider.
What to Watch For
Testosterone therapy should always be approached as a medical treatment and supervised. Regular lab monitoring is essential to track changes and ensure safety, as TRT can affect things like red blood cell count, fertility, and even cause skin changes or fluid retention. With careful management and prescribing, TRT can be safe and effective, but it should never be approached casually.
TRT Works Best With Lifestyle Medicine
Testosterone does not override poor sleep, inconsistent training, chronic stress, or poor nutrition. In fact, without addressing these factors, TRT often underperforms.
The best outcomes occur when TRT is paired with:
• Resistance training
• Adequate protein and calorie intake
• Sleep optimization
• Stress management
• Cardiovascular and metabolic health support
Is TRT Right for You?
To determine whether TRT is appropriate and how it fits into a broader plan for long-term well-being, you need to consider symptoms, lifestyle, and overall health .
If something feels off despite consistent effort, a comprehensive evaluation can help identify whether testosterone is part of the picture and what to do next. Contact Dr. Charlie Seltzer Lifesyle Medicine to find out how we can help you feel your best.
