What Does Low Testosterone Do to a Man?

Low testosterone has become the default explanation for almost anything a man dislikes about getting older: the flat mood, the softer erections, the stubborn belly, the gym plateau. Some of that blame is deserved. A lot of it is not.

Testosterone does specific things in the male body, and when it drops, specific things change. Knowing exactly which ones is the difference between fixing the real problem and spending a year chasing the wrong one.

What Testosterone Actually Controls

Testosterone is the primary male sex hormone, produced mostly in the testes under instruction from the pituitary gland. Its job list is short but wide-reaching: it drives sexual desire, maintains lean muscle mass and bone density, influences fat distribution, supports red blood cell production, and contributes to mood and mental energy.

Levels peak in early adulthood and then drift down. Both the NHS and Cleveland Clinic put the natural decline at roughly 1 percent per year from around age 30 to 40 onward. That slow slide is normal biology, not a disease.

Clinically low testosterone — male hypogonadism — is different. The American Urological Association uses total testosterone below 300 ng/dL as the threshold, and the Endocrine Society's clinical practice guideline uses the same cutoff. Critically, the number alone is not a diagnosis. You need a low level and symptoms that fit, confirmed on two separate early-morning tests, because testosterone peaks shortly after waking.

What Low Testosterone Does, System by System

Sex Drive and Erections

This is where testosterone's fingerprints are clearest. Research summarised in the Endocrine Society guideline found that sexual symptoms — low libido, poor morning erections, and erectile difficulty — clustered together in men with total testosterone under roughly 320 ng/dL. Below that line, desire drops measurably.

The nuance most men miss: testosterone governs wanting sex far more than it governs the hydraulics of an erection. Spontaneous and morning erections are testosterone-dependent, so those fade first. But the firmness of an erection during sex depends on arterial blood flow and on the pelvic floor muscles that clamp down on the veins to keep blood trapped in the penis. Those are mechanical systems, and they can weaken while your hormones sit perfectly in range.

That distinction matters because the two problems have completely different solutions. Our guide to erectile dysfunction treatment breaks down which approach fits which cause.

Muscle, Fat, and Bone

Testosterone is anabolic — it tells muscle tissue to build and maintain itself. When levels fall, lean mass and strength decline, and body fat tends to increase, particularly around the abdomen. The effect runs both ways, which is why it becomes a loop: excess abdominal fat converts more testosterone into estrogen, which suppresses testosterone further.

That loop shows up in the prevalence data. Hypogonadism caused by disease of the testes, pituitary, or hypothalamus affects under 1 percent of men. Hypogonadism associated with obesity — a body mass index of 30 or above — runs somewhere between 2 and 8 percent. For a large share of men with low readings, body composition is the driver, not a broken gland.

Bone is the quiet one. Testosterone, partly by converting to estradiol, maintains bone mineral density. Years of untreated deficiency raise fracture risk — a consequence men rarely connect to a hormone.

Mood, Energy, and Sleep

Low testosterone is associated with fatigue, low mood, irritability, and difficulty concentrating, as both Harvard Health and Cleveland Clinic describe. These symptoms are real, but they are also the least specific things on the list. Depression, poor sleep, chronic stress, thyroid problems, and simple overwork produce an identical picture.

This is exactly why a blood test matters. Assuming your flat energy is hormonal, when it is actually untreated sleep apnea, wastes months — and sleep apnea itself suppresses testosterone, so treating it can lift your levels without any hormone therapy at all.

What Low Testosterone Does Not Do

Here is where a lot of men get steered wrong.

It does not, by itself, make erections soft. If your desire is intact, you get erections, and the problem is that they lack rigidity or fade during sex, the limiting factor is usually blood flow and pelvic floor strength — not hormones. Testosterone therapy will not fix a mechanical problem.

It does not explain premature ejaculation. Ejaculatory control is a function of the bulbocavernosus and pubococcygeus muscles and learned reflex timing. Hormone levels are not the lever there.

It does not cause every case of fatigue after 40. Sleep debt, alcohol, sedentary work, and undiagnosed depression are all more common causes than hypogonadism.

The pelvic floor is the piece that gets missed most often. These are the muscles that surround the base of the penis and contract to trap blood during an erection. When they weaken — from age, sitting all day, or a sedentary decade — erections get softer and shorter-lived, regardless of what your bloodwork says.

The evidence here is solid. In a randomised controlled trial published in the British Journal of General Practice in 2004, Dorey and colleagues put men with erectile dysfunction through a structured pelvic floor muscle training programme. After six months, 40 percent had regained normal erectile function and another 35.5 percent had improved significantly — from exercise alone, with no medication and no hormones.

How to Tell Which Problem You Have

Run through this honestly:

1. Has your desire for sex dropped, or just your performance? Falling desire points toward hormones. Intact desire with weaker erections points toward mechanics.
2. Do you still get morning or spontaneous erections? If yes, your testosterone is likely doing its job.
3. Have muscle mass, strength, and body composition shifted noticeably over a year or two? That combination raises the odds of genuine deficiency.
4. Are you sleeping badly, drinking heavily, or carrying significant extra weight? All three suppress testosterone and all three respond to change.
5. Get the blood test. Two early-morning total testosterone measurements. Stop guessing.

If your levels come back low with symptoms that match, see a urologist or endocrinologist — that is a medical conversation about treatment. If your levels are normal and your issue is erection quality or control, the answer is training, not hormones. Our overview of kegel exercises for men covers exactly how to start, and what the pelvic floor muscles do explains the anatomy behind it.

What Recovery Actually Looks Like

For men whose low testosterone traces back to lifestyle, the fixes are unglamorous and effective: losing abdominal fat, getting seven or more hours of sleep, treating sleep apnea, resistance training, and cutting heavy alcohol use. Improvements typically show up over three to six months, not weeks.

For men whose real problem was mechanical all along, the timeline is different. Pelvic floor training usually produces noticeable change in four to six weeks of consistent daily practice, with the larger gains landing around the three-month mark — which matches the trial protocols in the research.

Either way, the honest first step is finding out which one you are dealing with.

Common Questions

Can low testosterone come back on its own? Yes, when the cause is reversible. Weight loss, better sleep, recovery from illness, and stopping medications that suppress testosterone can all bring levels back up. Deficiency caused by testicular injury or pituitary disease will not self-correct.

Does masturbation lower testosterone? No. Short-term hormone fluctuations around ejaculation are trivial and temporary. There is no credible evidence that normal sexual frequency changes baseline testosterone.

Will testosterone therapy fix my erections? It can help men with genuinely low levels whose main complaint is low desire. It is much less effective when desire is intact and the issue is erection firmness, because that is a circulatory and muscular problem. Therapy also suppresses natural production and fertility, so it is not a casual decision.

Do kegels raise testosterone? No, and any source claiming otherwise is guessing. Pelvic floor training does not change hormone levels. What it does is strengthen the muscles responsible for erection rigidity and ejaculatory control — a different mechanism aimed at a different problem.

How fast does testosterone drop with age? Roughly 1 percent per year after your thirties. That means a healthy 60-year-old typically sits well within the normal range. A sharp drop, or symptoms that appear over months rather than years, is worth investigating rather than writing off as ageing.

The Bottom Line

Low testosterone reliably does four things: it lowers sex drive, reduces spontaneous erections, shifts body composition toward fat and away from muscle, and thins bone over the long run. It is also blamed for a great deal it does not cause.

Get tested before you conclude anything. If your hormones are low, that is a medical problem with medical answers. If they are normal and your erections still are not what they were, the muscles doing the work are the place to look — and unlike your hormone levels, those you can train.