Why Have T Levels Dropped Nationally?

By The Vault Team

When it comes to testosterone, there are a lot of myths out there. But if you’ve heard a rumor that average T levels have gone down in men in the US, you’ve heard right. According to a study published in the Journal of Clinical Endocrinology and Metabolism, the average T levels in American men have rapidly declined over the past thirty years.

In the final installment in a series of free webinars, Vault’s Dr. Spar speaks with the EVRYMAN team about the reasons behind this national decline, its implications, and why it’s important to get your levels tested.

Testosterone’s Role After Puberty 

Many guys assume that T plays its biggest role during puberty, and understandably so. From a young age, we’re taught that T helps us develop some of our most distinguishably male characteristics, including testicles, body hair, and erections. But what many guys don’t realize is that T continues to play a critical role throughout our lives. 

As an adult, maintaining adequate T levels helps to support many crucial functions, including libido, muscle mass, strong bones, and cognitive thinking. Research also shows that having total serum T levels in the normal range, somewhere between 350-900 ng/dL, helps to prevent conditions like sarcopenia and cardiovascular disease

Why Have T Levels Dropped Nationally?

There are a few possible explanations behind the generational decline T levels, but here are some of the most compelling reasons to consider: 

Rise in Obesity

Since the 1970’s, obesity levels have been consistently rising in the US. The health risks of this trend are widespread—including an increase in type 2 diabetes, prediabetes, and heart disease—but it’s possible that it has also had an impact on national T levels in men.

This many happen because adipose tissue, or body fat, converts T to estrogen. In other words, men with more body fat convert more T to estrogen, initiating a vicious cycle of declining T and increasing estrogen. When men’s estrogen levels rise, the body stores more fat, exacerbating the cycle even more.

Exposure to Environmental Toxins

Plastics, pesticides, and other environmental chemicals are xenoestrogens—meaning they are hormonally active. These toxins act like estrogens in our body, helping to convert free T to estrogen. Our gradual increase in exposure to these toxins could be part of the reason why average T levels have dropped over time in the US. In addition to the changes in our environment, we’re also eating a lot more processed foods than our grandparents did. Foods like soy protein isolate—which is popular in many protein powders and shakes—are estrogenic and can mess up the balance of estrogen and T in our systems. 


Chronic stress is on the rise, having a noticeable impact on our emotional and physical health. Though resources for managing stress are growing, data from the American Psychological Association shows that Millenials and Gen Xers are still among the most stressed out generations in history. Living in these uncertain times can affect our mood, gut health, and—you guessed it—T levels. When stressed, the hypothalamus switches on fight-or-flight mode, sending the message to the testicles to blunt reproductive drive and stop production of T. 

Growing Responsibilities of Fatherhood

In good news, today’s fathers are playing a bigger role in their children’s lives than ever before. Surprisingly, it may also be lowering their T. In the first large study to measure T levels in men before and after having children, data showed that fathers who play an active role in their children’s lives have lower T levels. Though the precise reasons are still unknown, evolution may help explain this hormonal change: if you’re more involved as a parent, your body may prioritize caretaking over progeny, and reduce the hormone primarily responsible for reproductive drive accordingly.

The Impacts of Low T

Contrary to popular assumption, T isn’t just responsible for sexual performance. Yes, it helps to drive a healthy libido and strong erections, but T supports other important functions, too. Like most hormones—including insulin, cortisol, and thyroid hormone—T has receptors in tissues all over the body. When T levels are low, that can have a ripple effect on hormones throughout the body, which can cause low energy, reduced muscle mass, brain fog, change in mood, and a higher risk of heart disease and diabetes. 

Low T can seriously affect your quality—and quantity—of life, and should be taken as seriously as any other hormone dysfunction.

How T Replacement Works

Though there are supplements that can help with the symptoms of low T, there are no supplements that will safely and substantially raise T. If your levels are low, and you’ve already tried improving your diet, exercise, sleep, and stress management to no avail, the next best option is testosterone replacement therapy, or TRT. 

Put simply, TRT safely takes over the body’s production of T. Unlike other hormonal treatments, the T is bioidentical to the molecule your body naturally makes, rather than a fake form of the hormone, as is the case with anabolic steroids

At Vault, we prescribe subcutaneous injections, because TRT is most effective and best absorbed when injected. Once you get started on TRT, your team of Vault practitioners will monitor your progress and check-in after about six weeks. Best of all—most guys see an improvement in some of their symptoms after just two weeks.

Getting Started

We know that 40% of guys over 40 have low T. With that in mind, it’s a good idea to get your total T levels checked about once a year once you hit 40. Thankfully, Vault makes testing and treating T easier than ever. We schedule appointments where you are, provide fast diagnoses and lab results, and deliver prescriptions right to your door. With Vault, you’ll also have 24/7 access to our health care providers so you can stay on top of your progress.

Want to get started? Book your first online visit today. 

DISCLAIMER: This article is for general information purposes only, does not constitute medical advice and is not intended to be relied upon for medical diagnosis or treatment.  If you are experiencing an emergency, dial 911 or contact a medical practitioner immediately.  Consistent with Vault Health, Inc.’s website privacy policy, Vault Health, Inc. is not responsible for the privacy practices or the content found at links to other websites.

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