It’s Totally Possible to Have Optimal Testosterone After 40
Maintaining optimal testosterone levels after 40 is absolutely possible. The key is to ensure your body keeps producing it and that it's available for use.
If your testosterone is low and you’re under 70, it's usually a production issue.
When I tell guys that the natural approach to fixing low T starts by identifying why it's low, they often say, “Isn’t it just my age? I thought low T was a normal part of being over 40.”
While it’s common, it’s definitely not normal.
Take a recent conversation I had with a potential client. He was 67 years old, 40 pounds overweight, and prediabetic, yet his total testosterone was 465 ng/dL. He wasn’t taking any supplements or strength training, so imagine how much more testosterone he could produce if he optimized his health. The point is, this man did not have low T, and he’s almost 70.
However, about 3 in 10 men over 40 do have low T—defined as levels below 300 ng/dL on two separate tests, along with symptoms. So, what’s causing this?
Why Do Men Have Low T After 40?
A large 2023 study looked at the root causes of low testosterone in over 25,000 men. It identified six key factors contributing to low T:
High BMI (overweight or obese)
Low exercise levels
High blood pressure
A history of smoking, heart disease, cancer, or diabetes
Taking statins or psychiatric medications
Marriage
These issues—whether it’s excess weight, inactivity, or prediabetes—are caused or worsened by diet and lifestyle, not simply by age. While this might sound discouraging, it's actually good news because it means you can reverse these factors and restore your testosterone production back to normal.
Think of these problems as kinks in a hose, a dam blocking a river, or a clogged fuel line. Your body is still capable of producing testosterone, but something is stopping it. What I’ve found after helping hundreds of guys with low T is that once you identify and then clear these obstacles, you can maintain T production as you age.
How to Naturally Support Testosterone Production
1. Cholesterol: The Raw Material for Testosterone
Testosterone is made from cholesterol in a process called steroidogenesis, which also produces cortisol and estrogen. If you’re on a statin or have low HDL cholesterol, it can interfere with this process. Your body needs cholesterol, and maintaining a nutrient-dense diet with minimal processed carbs is often more effective than relying on medications to manage cholesterol.
2. The Brain-Testes Connection: The HPG Axis
The hypothalamic-pituitary-gonadal (HPG) axis is the signaling system between your brain and your testes that tells your body to produce testosterone. Think of it like your brain telling you you're thirsty—you get the message, drink some water, and the feedback loop is satisfied.
Testosterone production relies on signals like Gonadotropin-Releasing Hormone (GnRH) and Luteinizing Hormone (LH). Unfortunately, these signals can be disrupted by chronic stress, which prevents your testes from getting the message, reducing testosterone production.
3. Healthy Leydig Cells: The Testosterone Factories
Leydig cells in your testes are responsible for making testosterone. To function well, these cells need to be healthy, but they’re often disrupted by:
Inflammation
Insulin resistance (like prediabetes or diabetes)
Environmental toxins (phthalates, heavy metals, pesticides)
Leydig cells can handle a lot, but when overwhelmed by inflammation or toxins, they stop functioning properly, and testosterone production declines.
4. Vitamins and Minerals: The Building Blocks
Most guys I work with don’t realize how important vitamins and minerals are for testosterone production. For example, low vitamin D levels are associated with low T, and supplementing with vitamin D can raise your levels if you’re deficient. Other key nutrients include zinc, magnesium, and omega-3 fatty acids.
Making Sure You Can Use the Testosterone You Make
Once your body is producing testosterone, the next step is ensuring it's usable. This means having enough free testosterone—the testosterone not bound to proteins like SHBG or albumin. Ideally, about 1-2% of your total T is free testosterone.
To optimize free testosterone, you need to be metabolically healthy. Here’s what that looks like:
Waist size under 40 inches (ideal is half your height in inches)
HDL cholesterol over 40 mg/dL (ideal is 50+)
Fasting blood sugar under 100 mg/dL (optimal is 80)
Triglycerides under 150 mg/dL (optimal is below 100)
Blood pressure under 130/85 (optimal is 120/80)
If three or more of these markers are out of range, you likely have metabolic syndrome, which can significantly affect testosterone. Visceral fat, for example, secretes an enzyme that converts testosterone into estrogen, creating a cycle of weight gain and low T. In extreme cases, this can cause men to develop breast tissue.
This explains why testosterone alone via TRT won’t fix the underlying issue. You need to make sure it's not being converted into something else.
The Three Boxes You Need to Check for Optimal T After 40
Fix what’s blocking testosterone production – Address the factors that are preventing your body from producing testosterone.
Ensure you have the right building materials – Make sure your body has the necessary vitamins, minerals, and cholesterol to support healthy testosterone production.
Make sure the testosterone isn’t being bound or converted – Optimize your metabolic health so you can use the testosterone your body makes.
By addressing these areas, you can maintain optimal testosterone levels—no injections needed—well into your 70s.
References
Marriott, Ross, et al (2023). Factors Associated With Circulating Sex Hormones in Men : Individual Participant Data Meta-analyses. Annals of internal medicine. 176. 10.7326/M23-0342.
Aitken, R. J., Roman, S. D. (2008). Reproduction, 136(2), 173–185. doi:10.1530/REP-07-0582
Dhindsa, S., et al. (2004).Testosterone Deficiency in Men With Type 2 Diabetes. Endocrine Practice, 10(4), 367–374. doi:10.4158/EP.10.4.367
Gray, P. B., et al. (2018). Chronic Stress, Testosterone, and Hypothalamic-Pituitary-Gonadal Axis Dysfunction. Frontiers in Neuroendocrinology, 49, 58–70. doi:10.1016/j.yfrne.2017.12.003
Skakkebaek, N. E., et al. Endocrine Disruptors and Male Reproductive Health.(2016). Nature Reviews Endocrinology, 12(7), 410–424. doi:10.1038/nrendo.2016.57
Prasad, A. S., et al. (1996).Effect of Zinc and Magnesium Supplementation on Testosterone Levels. Nutrition, 12(5), 344–349. doi:10.1016/S0899-9007(96)00049-6