If you're tired all the time, losing muscle you used to have, gaining weight around the middle without eating any differently, or noticing a drop in libido — you're not alone, and you're not just "getting old." A meaningful share of adult men have clinically low testosterone (sometimes called "Low T" or hypogonadism), and it's one of the most under-diagnosed contributors to how a lot of guys feel in their late 30s, 40s, and beyond.
Here's what to actually look for, how the diagnosis is really made, and whether testosterone replacement therapy (TRT) might make sense for you.
Common signs of low testosterone
Testosterone influences a lot more than just libido. Common symptoms of low testosterone include:
- Persistent fatigue and lower energy than you're used to
- Reduced libido or sexual function
- Loss of muscle mass or strength, even with regular exercise
- Increased body fat, particularly around the midsection
- Mood changes — irritability, low motivation, or feeling "flat"
- Poor sleep quality
- Difficulty concentrating or "brain fog"
Any one of these symptoms in isolation can be caused by other things. But when several of them show up together and persist, it's worth a conversation with a physician.
How Low T is actually diagnosed
Here's an important point that a lot of the flashier online TRT sites gloss over: a real diagnosis of low testosterone requires both symptoms and confirmed lab values. The medical standard is generally two separate morning blood tests showing testosterone below the accepted threshold — because testosterone naturally fluctuates through the day, a single afternoon draw can be misleading.
A responsible evaluation also looks at other things that can either mimic or cause low testosterone, including thyroid problems, sleep apnea, poor sleep quality, obesity, depression, and chronic illness. Sometimes the underlying cause is treatable in a way that restores testosterone naturally, without needing lifelong replacement therapy.
Who benefits from TRT — and who doesn't
For men with confirmed clinical low testosterone and bothersome symptoms, TRT can be genuinely life-changing: better energy, improved libido, easier maintenance of muscle mass, better mood, and better sleep. Those outcomes are well-documented in the medical literature.
That said, TRT isn't right for everyone. It's generally not appropriate for:
- Men with active prostate cancer
- Men with untreated severe sleep apnea
- Men with uncontrolled polycythemia (high red blood cell count)
- Men actively trying to father children in the near future (TRT suppresses natural sperm production)
A physician will screen for these before recommending treatment.
What ongoing TRT actually involves
TRT isn't a one-time prescription. Safe, effective testosterone therapy requires ongoing monitoring: periodic labs to check testosterone levels, hematocrit, PSA, and estradiol, along with follow-up conversations about how you're feeling. This monitoring is standard of care, and it's what separates a legitimate TRT practice from the kind of high-pressure "sign up and we'll ship your testosterone forever" operations that give the field a bad name.
How Simply Medicine can help
If you think you might have symptoms of low testosterone, a telemedicine evaluation is a straightforward way to talk through what you're experiencing, get the appropriate labs ordered, and — if TRT is indicated — start treatment with proper monitoring built in. If Low T isn't the actual cause of your symptoms, we'll be honest with you about that too, and help you think through what might be.
Sources
- American Urological Association, Clinical Practice Guideline: Evaluation and Management of Testosterone Deficiency — auanet.org
- Endocrine Society, Clinical Practice Guideline: Testosterone Therapy in Men with Hypogonadism — endocrine.org
- Forbes Health, "How To Find The Best Online TRT Clinic," 2026 — forbes.com/health