Testosterone Replacement Therapy Benefits: What Can TRT Actually Improve?

Testosterone replacement therapy is often made to sound like a fix for every problem men run into with age: low libido, tiredness, weight gain, poor concentration and erection problems. Is it as good as they say?

Testosterone is a hormone that is found in both males and females, although it is found in much smaller amounts in females. It plays an important role in men’s health, affecting everything from energy levels to mood. When levels fall below normal, it can lead to symptoms like fatigue, reduced libido, and loss of muscle mass. Testosterone will naturally taper off as a man ages although other factors can also cause hormone levels to drop, such as injury to the testicles, medications, certain chronic health conditions, stress and many other reasons could result in low testosterone. Testosterone Replacement Therapy (TRT) can help bring your levels back to normal and address issues caused by low testosterone, improving your overall well-being and quality of life.

Sexual desire is one of the areas where TRT has the clearest evidence behind it.

The Testosterone Trials tested testosterone gel against placebo in 790 men aged 65 and over with testosterone below 275 ng/dL, roughly 9.5 nmol/L. ^[1] A later study (TRAVERSE) of 1,161 men with established cardiovascular disease or at high risk of it, low testosterone and low libido was run. ^[2]

Both studies found that TRT improved sexual desire, sexual activity and wider symptoms of testosterone deficiency compared with placebo. 

The Testosterone Trials study found that TRT did help with erectile function but the TRAVERSE study found that erectile function did not improve. These two different findings are possibly due to low testosterone reducing your interest in sex, and replacing the testosterone directly increases interest back up to normal levels, but an erection also depends on healthy blood vessels and nerves. Diabetes, cardiovascular disease (which were present in the TRAVERSE study) medication, stress and anxiety can all cause erection problems, so TRT may not necessarily replace treatments such as sildenafil or tadalafil.

TRT can increase lean body mass and reduce body fat in men with low testosterone. However, do not treat it as a weight-loss treatment or a bodybuilding shortcut; taking TRT will not turn you into Arnold Schwarzenegger.

A meta-analysis of 59 trials found improvements in lean and fat mass without significant changes in overall body weight, BMI or waist circumference. Meaning your body composition may change even when the number on the scales does not, as you lose fat but gain lean muscle. ^[3]

TRT may help restore muscle that was being lost because testosterone was low, but it does not replace a good diet and regular resistance training.

The short answer is possibly, it is not a guarantee in every man and different men respond differently. In the Testosterone Trials, treatment did not significantly improve energy, although it produced small improvements in mood and depressive symptoms. A separate part of the trial found no improvement in memory or other tested areas of cognitive function. ^[4]

Tiredness, low mood and poor concentration can also be caused by poor sleep, sleep apnoea, depression, stress, anaemia, thyroid problems or medication. So just raising testosterone will likely not help if your mood/fatigue is caused by poor sleep or thyroid for example.

Some of TRT’s effects are more likely to show up on a blood test or scan than in how you feel day to day.

In the TRAVERSE trial, 41% of men who were anaemic at the start were no longer anaemic after six months of testosterone treatment, compared with 27.5% of those using placebo. ^[2] TRT can also increase bone mineral density in men with low testosterone.

However, better bone density should not be confused with proven fracture prevention. In a separate study of 5,204 men, TRT did not reduce fractures. Clinical fractures occurred in 3.50% of the testosterone group and 2.46% of the placebo group over a median follow-up of just over three years, most of the fractures followed a fall and the most frequent sites included the ribs, wrists and ankles. ^[5] The result of the study looks a bit backwards as it shows that fractures were slightly higher in the TRT group, one suggestion for this is that men may have become more active before their bones had derived any meaningful protection, but the trial did not collect enough information on activity and falls to prove that explanation. It is also important to note that just because this study found no relation to reducing fractures, it may still be valuable in men with severe or longstanding hypogonadism who are losing bone because they lack testosterone. Restoring normal testosterone could prevent further deterioration and partially restore bone that has been lost.

TRT will not reliably correct erectile dysfunction caused by poor circulation, tiredness caused by poor sleep, weight gain without lifestyle changes or poor concentration in someone whose testosterone is already normal.

It can also suppress sperm production, so testosterone therapy is generally not started in men planning fertility. Anyone using TRT needs regular blood tests and clinical reviews to check that treatment is both helping and remaining safe.