by TC Luoma
The TRT Timeline
Rarely does a prescribing physician tell you what to expect from testosterone replacement therapy. Here's what you need to know.
There are a lot of misconceptions about how long it’ll take for the effects of testosterone replacement therapy (TRT) to kick in. Granted, most men realize that the appearance of new muscle and the loss of old fat takes a bit longer than a few weeks or months, but these same men often have completely unrealistic expectations of how quickly it’ll take for sexual performance to ramp up.
Many expect that their thoughts will immediately begin to be consumed with fantasies of women with terrific conformations, and their previously moribund manhood will rise like Nosferatu from their underpants-graves to hunt their fleshy bounty.
I suppose this latter misconception and other mistaken ideas about TRT stem from science fiction movies or series where someone swallows a pill or injects green fluid into their neck and immediately transmogrifies into something terrible and formidable, but TRT isn’t like that.
While its effects are multifaceted and significant, each of its effects, generally speaking, has its own timetable. Some, like unexpected bursts of energy, come quickly, but others, like libido, are more mercurial and arrive in their own due time.
And while there hasn’t been any research specifically devoted to charting TRT’s timetable of effects, plenty of studies have suggested, as an aside or footnote, approximately how long it takes for testosterone to do its magic.
However, it’s tricky coming up with exact timelines. For one thing, truly hypogonadal guys will notice changes a lot quicker. This stands in stark contrast to the guy who just wants to jack up his testosterone levels a bit so that he can just be more – more man, more gym beast, more lover. In other words, the less hypogonadal you are before starting TRT, the smaller the increase in circulating T, and the longer the duration of treatment needs to be before changes are detected.
With that in mind, here’s a general rundown of what some studies say, as reported by Saad, et al, in the European Journal of Endocrinology.
The TRT Timeline on Muscle Mass and Strength
Most of the effects on TRT and muscle mass/strength are dose-related. If you’re just testosterone spritzing as opposed to taking a testosterone bath, there’s not going to be much of a discernable change.
For instance, if you look at the body of studies, the changes in muscle mass ranged from 0.4 kilograms to a sizeable 16.4 kilograms (the latter taking place over the course of a year). Likewise, increases in leg press strength ranged from 11.6 kilograms to 76.5 kilograms.
Several studies used between 50 mg. of testosterone gel a day to 150 mg. a day, and those almost universally showed significant increases in leg press strength, bench press strength, and stair climbing power (?) within 6 months.
Another, using 200 mg. of testosterone enanthate every two weeks, found that strength and mass continued to increase for the first 12 months of TRT but largely fizzled out after that.
Despite those vague observations, some trends and commonalities have been noted, mainly that the effects of TRT on muscle strength and size are easily observable after 12-20 weeks, while maximum effects are achieved after 6 or 12 months. (TRT-induced gains might continue after that, but only at a snail’s pace, unless the dosage is upped).
The TRT Timeline on Libido and Erections
Libido, erections, and all things sexual are complex beasties. Low libido can correlate with testosterone levels but can be exacerbated by medical/psychological conditions such as diabetes or depression. I don’t mean to be overly glib here, but it can also be affected by having a partner who regards sex as just another household chore, or one that looks like a sack of potatoes when they put on fishnet lingerie.
All that goes double for erections, which are mightily influenced by poor arterial endothelial function and health, neuronal integrity, psychological factors, and of course testosterone concentrations, in addition to all the stuff listed in the previous paragraph.
What I’m trying to say is that TRT is not a cure-all as far as libido and erections are concerned. That said, studies have revealed some generalities. Most of the time, libido and sexual thoughts/fantasies manifest pretty quickly. Thoughts of sexy sugar plum fairies wearing thongs start to manifest themselves within 21 to 30 days, but some studies note these effects only after about 3 months.
Similarly, these same TRT sugar plum fairies tap their wands on underperforming penises after about 3 weeks, often manifesting in morning wood.
Maximal effects, however, are usually seen between 3 and 6 months, but it may take as long as a year for certain cases. Remarkably, one study showed that administering testosterone undecanoate (TU) to patients with “veno-occlusive dysfunction” (bad plumbing) restored full erectile function in a minimum of 3 months and a maximum of 11.5 months.
The TRT Timeline on Body Comp
Testosterone, bless its heart, is a major player in obesity, glucose control, and lipid metabolism. Often, upon administering TRT, there’s an increase in muscle mass and a concurrent loss of body fat, often resulting in a bodyweight that doesn’t change (especially in those that don’t practice resistance training).
Fat, at least in males, accrues preferentially in the mid-section, and this is where TRT does its best fat-reducing work. Studies show a decrease in waist circumference in approximately 3 months, continuing for over 24 months.
While this slimming effect is often chalked up to increases in metabolism or energy expenditure, it’s more likely caused by biochemical influences. In particular, testosterone “regulates lineage determination in mesenchymal pluripotent cells by promoting their commitment to the myogenic lineage and inhibiting their differentiation into the adipogenic lineage through an androgen receptor-mediated pathway.”
Sorry for throwing such an arcane sentence at you, but I was struck by its biochemical “poetry” and just had to throw it in. Anyhow, it means that testosterone can tell certain cells to turn into muscle cells instead of fat cells, which explains how TRT can have such dramatic effects on body composition.
The TRT Timeline on Cholesterol and Triglycerides
To this day, many doctors operate under the belief that TRT has ill effects on blood lipids, but the opposite is largely true. Decreases in total cholesterol have been noted in as little as 4 weeks, but most of the time, it takes up to 3 months for that number to start to nosedive.
As far as TRT’s effects on the two main cholesterol fractions, LDL usually shrinks over an impressive 24 months, while HDL continually increases over the same amount of time.
Similarly, triglyceride levels start to optimize in as little as 4 weeks but may continue to optimize for up to 24 months.
The TRT Timeline on Blood Pressure and Other Cardiovascular Factors
Similar to cholesterol and triglycerides, doctors often assume TRT raises blood pressure (BP), but again, the opposite is largely true. Decreases in diastolic BP (the “bottom” number in a BP reading) have been observed between 3 and 9 months, bottoming out after about 12 months. While not as common, systolic BP sometimes responds to TRT the same way (drops).
Likewise, decreased resting heart rate has been observed after 40 to 44 weeks. More impressively, decreases in arterial stiffness have been observed in as little as 48 hours (the less stiff your arteries, the less strain on your heart and the stiffer your erections).
The blood pressure thing may not be true, though, for those who put on a tremendous amount of muscle mass via TRT because just being bigger can increase BP.
The TRT Timeline on Mental State
A lot of people still think that testosterone will cause you to kill your parents and run over small woodland creatures in a 4-wheeler while laughing maniacally. But paradoxically, it’s often men with low testosterone levels that are moody, depressed, and even angry, while men with normal or high testosterone levels are generally sociable and gregarious.
A UCLA researcher found that men with low T were indeed likely to be snarkier and more aggressive than men with high T, but once the snarky ones received T replacement, their attitude and anger disappeared.
Low T men are also more likely to be depressed, but often their depression, like their possible snarkiness, disappears with TRT. Some studies found that testosterone causes depression to lift in as little as 3 to 6 weeks, but will most likely take 18-30 weeks to do its personality-modifying thing.
TRT also appears to play a role in what I call “appropriate aggressiveness.” What I mean by that is that it’s sometimes appropriate to cry havoc and let slip the dogs of war. I’m not talking about being a hair-trigger DB who coldcocks anybody who has the temerity to bump into him, but sticking up for oneself when it’s called for. This might include standing up to a dickish boss who demands you work weekends without getting paid for it, telling the neighbor who practices playing his Taiko drums at 2 AM to knock it off, or something as simple as giving the finger to your least favorite politician.
This sort of change in personality, along with the ability to be quicker in making decisions or better at critical thinking, might take as long as a year to kick in (if it were absent in the first place).
TRT Timelines: The ADD Version
Here, in bullet-point form, is a synopsis of what you can expect during the TRT period (including some effects I didn’t discuss):
WEEK 1:
- Occasional bursts of energy, kind of like human puppy runs.
- Improved insulin sensitivity (only detectable with a blood test).
WEEK 3:
- Possible lifting of depressive fog.
- Lower levels of stress hormones (again, this would only be detectable with a blood test).
WEEK 4:
- The erection fairy comes (leave a quarter and a prophylactic under the pillow).
- Cholesterol may begin to ease up (blood test).
WEEK 6:
- Possible total lifting of depression.
- You receive more party invitations, Mr. Fun Guy, you.
3 MONTHS:
- Waistline is noticeably trimmer.
- Blood pressure has likely dropped.
- Red blood cell production has increased.
6 MONTHS:
- Bone density has increased measurably.
- Maximum sexual benefits have likely kicked in.
12 MONTHS:
- Mood-wise, you might be a different person.
- Mental acuity tops out. Decision-making is quicker, appropriate aggressiveness is evident.
- More muscle mass, less body fat.
- Deeper sleep.
- Improved glycemic control.
- Increased exercise capacity.
- More studly in general.
The Goldilocks Approach
One thing I didn’t mention is mode of TRT, i.e., gels/creams or injections. The timeline should be approximately the same with either modality, but gels/creams may be a little tricky because absorption rates may vary on how well you applied them, how thick your dermis is, or whether you bathed and scrubbed in the last month.
I also need to reiterate that most of the observations regarding TRT timelines have been made on truly hypogonadal men, not guys just looking for a boost. “In other words, signs and symptoms of testosterone deficiency appear at different threshold values of circulating testosterone (Saad).”
For example, if you weren’t truly suffering from low testosterone, the effects of TRT on, say, depression, might not be as dramatic as if you were someone with normal values who just wanted a little help in putting on muscle and losing fat.
The timeline or intensity of effects is also highly dependent on dosage. Most of the observations reported in this article were made in men who were receiving adequate dosing. As with any drug or supplement, the Goldilocks approach seems prudent: not too little, not too much, but just the right amount (which should be determined by symptoms rather than some doc’s opinion of how much to give).
One thing should be clear, though: TRT, in most cases, has something to offer for a whole lot of people, especially those that truly need it.
References
References
- Saad F et al. Onset of effects of testosterone treatment and time span until maximum effects are achieved. European J of Endo. (2011) 165 675-685.
- Wang C et al. Testosterone replacement therapy improves mood in hypogonadal men–a clinical research center study. J Clin Endocrinol Metab. 1996 Oct;81(10):3578-83. PubMed.