TRT - How Healthy, Lean and Muscular Will Testosterone Replacement Make You? Data from Recent Meta-Analysis

TRT - What to expect in terms of its effects on a man's body composition?

If you hear people talk about "gear" (=performance enhancing drugs | PED), you get the impression that one injection of testosterone, nandrolone and co would turn a scrawny beginner into an Olympian. Reality, however, looks much different ... in fact, the number of people who ruin their health with (often oral) designer steroids without seeing any of the results they expect has been increasing continuously over the past years (Baker. 2006a,b; Graham. 2008; Rahnema. 2014) and that despite the fact that the "Anabolic Steroid Control Act" of 2004 was originally meant to prevent exactly that from happening (Herschthal. 2012).

In spite of the fact that the introduction of today's SuppVersity article focused on PED, the purpose of the meta-analysis and thus its summary was "systematically review [...] available observational and register studies reporting data on body composition in studies" in men with low or at least suboptimal testosterone levels.

This is what most studies were lacking: Exercise to shed fat and gain muscle.

Tri- or Multi-Set Training for Body Recomp.?

Alternating Squat & Blood Pressure - Productive?

Pre-Exhaustion Exhausts Your Growth Potential

Full ROM ➯ Full Gains - Form Counts!

Battle the Rope to Get Ripped & Strong

Hula Hooping to Spot Reduce in the Midsection

The original meta-analysis by Corona et al. (2016) was published in the Journal of Endocrine Investigation, only a few days ago. It involved "an extensive MEDLINE, Embase, and Cochrane search [that] was performed including the following words: testosterone and body composition. And is thus not focussing exclusively on testosterone as a "new anti-obesity medication", which is how the authors refer to it in the very first sentence of the abstract, because "all observational studies comparing the effect of TS on body weight and other body composition and metabolic endpoints were considered" (Corona. 2016) in the scientists' meta-analysis. Here's an overview of the studies, their design an results, as they were summarized by Corona et al.:

• 

  Suggested Read: Testosterone Gel Augments Increases in Lean Mass Gains (+3.9kg in 6 Months) in Older Intensely Training Men, but Testim Blocks Decrease in Marker of Heart Disease Risk | more

  Valdermasson et al. (1987) - no placebo group, 10 subjects, 9 months, late onset hypogonadism (LOH) w/ baseline T of 1.8 nmol/l receiving TE 250 mg/3–4 weeks
• Rebuffé-Scrive et al. - no placebo group, 11 subjects, 1.5 months, mean age 42y, overweight/obese subjects, mean baseline T 13.8nmol/l, receiving TU 120–160 mg/day
• Forbes et al. (1991) - no placebo group, 7 subjects, 4 months, healthy, normal T levels, receiving TE 42 mg/kg/week
• Marin and Krotkievski et al. (1992) - no placebo group, 11 subjects, 1.5 months, mean age 42y, obese subjects, low T at 13.8 nmol/l, receiving TU oral 160 mg/day
• Marin and Krotkievski et al. (1996) - no placebo, 8 subjects, 3 months, mean age 42y, obese, low T at 14.1 nmol/l on T gel 250 mg/day
• Brodsky et al. (1996) - no placebo, 5 subjects with late onset hypogonadism (LOH) and T-levels of only 3.7 nmol/l on TC 3 mg/kg/2 weeks
• Katznelson et al. (1996) - no placebo, 29 subjects, 13 months, mean age 57, LOH w/ testosterone levels of 6.4 nmol/L on TE or TC 100 mg/week
• Wang et al. (1996) - no placebo, 67 subjects, for 6 months, LOH w/ starting T levels of 4.1 nmol/l taking T sublingually at 15 mg/day
• Zgliczynski et al. (1996) - no placebo, 22 subjects, 12 months, mean age 58.5y, normal elderly men with very low T (4.3 nmol/l) taking TE 200 mg/2 weeks
• Bhasin et al. (1997) - no placbeo, 7 subjects, 2.5 months, mean age 34.7y, LOH at initially 2.5 nmol/l receiving TE at a dosage of 100 mg/week
• Tan et al. (1998) - no placebo, 11 subjects, 4 months, mean age 33.3y, LOH w/ initially 5.5 nmol/l receiving TE at a dosage of  250 mg/4 weeks
• Brill et al. (2002) - no placebo, 10 subjects, 1 month, mean age 68.1y, but T-levels of 15 nmol/l treated with T patches at 5 mg/day
• Minnemann et al. (2007) - no placebo 25 subjects, mean age 57y w/ LOH and initial T levels of pretty high 14.3 nmol/l receiving TU 1000 mg/12 weeks from week 6

• 

  Suggested Read: Tribulus Boosts Testosterone (+12%), IGF-1 (+20%), Sheds 2kg (7%) Body Fat and Maintains Lean Mass in 12 Wk RCT | more

  Naharci et al. (2007) - no placebo, 24 subjects, 6 months, mean age 20.7y, low T at 5.7 nmol/l treated with mixed ester at 250 mg/3 weeks
• Saad et al. (2007) - no placebo, 28 subjects, 13 months, LOH with erectile dysfunction (ED), low  T at initially 7.5 nmol/l treated with  TU at 1000 mg/12 weeks from week 6
• Saad et al. (2008) - 27 subjects, 9 months, mean age 60y LOH with ED and initial T levels of 7.5 nmol/l treated with TU 1000 mg/12 weeks from week 6 or T gel 50mg/day
• La Vignera et al. (2009) - no placebo, 7 subjects, 3 months, mean age 58y, LOH with MetS and unknown baseline T levels treated with T gel 50 mg/day
• Moon et al. (2010) - no placebo, 133 subjects, 6 months, mean age 54y baseline T of 8.6 nmol/l treated with TU at 1000 mg/12 weeks from week 6
• Permpongkosol et al. (2010) - no placebo, 161 subjects, 13.5 months, mean age of 60.4y and LOH consulting urological center w/ T at 9.4 nmol/l on TU 1000 mg/12 weeks from week 6
• Garcia et al. (2011) - no placebo, 29 subjects, treated for 25.5 months,  mean age 55.5y, LOH and diabetes, no baseline T available, treated with TU 1000 mg/12 weeks from week 6
• Schwarz &Willix (2011) - no placebo, 56 subjects, 18 months, mean age 52.3y, overweight or obese with baseline T of 15 nmol/l receiving TC 80–200 mg/week + diet + training
• Arafa et al. (2012) - no placebo, 56 subjects, 12 months, mean age 55.5y w/ T2DM and unknown baseline T treated w/ TU 1000 mg/12 weeks from week 6
• Schroeder et al. (2012) - no plaebo 29 subjects, 4 months, mean age 71y, baseline T of 13.1 nmol/l treated with T patch 5 or 10 mg/day
• Jo et al. (2013) - no placebo, 18, 26.8 months, mean age 35.9y and suffering from Klinefelter syndrome, with low T at 3.1 nmol/l at baseline treated w/ TU 1000 mg/12 weeks from week 6

What is the Klinfelter syndrome? That's a genetic disorder that affects males. Klinefelter syndrome occurs when a boy is born with one or more extra X chromosomes. Most males have one Y and one X chromosome. Having extra X chromosomes can cause a male to have some physical traits unusual for males.

• Ko et al. (2013) - no placebo, 246 subjects, 14.7 months, mean age 58.5y  treated w/ TU 1000 mg/12 weeks from week 6
• Rodriguez-Tolrà et al. (2013) - no placebo, 50 subjects, 12 months, mean age 59.1y, LOH, mean T at baseline 10.2 noml/l treated w/ T gel 25–100 mg/day

• 

  Suggested Read: Hormonal Response to Exercise, Revisited: A Consequence, not a Determinant of Your Mood, Effort & Performance | more

  Saad et al. (2013) - no placebo, 255 subjects, 60 months, mean age 58y, mixed urological population, low T at 10.0 nmol/l treated with TU 1000 mg/12 weeks from week 6
• Tirabassi et al. (2013) - no placebo, 15 subjects, 18.5 months, mean age of 55.7y, LOH w/ baseline T levels of 5.2 nmol/l on TU 1000 mg/12 weeks from week 6
• Zitzmann et al. (2013) - no placebo, 1438 subjects, 10.5 months, mean age 49.2y, LOH w/ baseline T levels of 9.6 nmol/l on TU 1000 mg/12 weeks from week 6
• Francomano et al. (2014) - no placebo, 20 subjects, 60 monhts, mean age 57.5y, MetS and basline T of 8.3 nmol/l on TU 1000 mg/12 weeks from week 6
• Pexman-Fieth et al. (2014) - 669 subjects, 6 months, 53y, LOH on  T gel 50, 75 or 100 mg/day
• Yassin et al. (2014) - no placebo, 261 subjects, 54 months, mean age 59.5y, LOH w/ baseline T levels of 7.7 nmol/l treated w/ TU 1000 mg/12 weeks from week 6
• Zitzmann et al. (2014) - no placebo, 381 subjects, treated for 60 months, mean age 42.6y w/ LOH and low T at 5.2 nmol/l on TU 1000 mg/12 weeks from week 6

Figure 1: Influence of trial duration (a, b), age (c, d) and testosterone levels at enrollment (e, f) on weighted mean differences (with 95 % CI) of body weight (a, c, e) and waist circumference (b, d, f) at endpoint after testosterone supplementation. The size of the circles reflects the sample dimension (Corona. 2016).

Why did the scientists prefer observational trials over RCTs? "The peculiar study design of these RCTs might, as the authors point out justify the lack of efficacy of testosterone supplementation on weight parameters in previous meta-analyses. In fact, RCTs are performed under idealized and rigorously controlled conditions, which are different from everyday clinical practice. Hence, results of RCTs offer an indication of the efficacy of an intervention rather than its effectiveness in everyday practice. [...] In contrast, observational and register studies maintain the integrity of the context in which medical care is provided. As a result, whereas RCTs provide an indication of the minimal effect of an intervention, observational studies offer an estimate of the maximal one," Corona et al. write.

Table 1: Number and proportion (%) men reporting use of AAS, life-time, past 12 months and past 30 days, in different subgroups (Leifman. 2011).

All in all, we are talking about 32 out of 824 initially retrieved articles and 4513 patients whose mean age of 51.7 ± 6.1 years is yet far above that of the average PED (ab-)user whose age appears to be somewhere between 25 and 29, likely to have visited only "compulsory school" and a friend of alcohol and dietary supplements (Leifman. 2011 | see Table 1) and a very obvious result, i.e. that the supplementation of testosterone "was associated with a time-dependent reduction in body weight and waist circumference (WC).

To be more specific, "[t]he estimated weight loss and WC reduction at 24 months were −3.50 [−5.21; −1.80] kg and −6.23 [−7.94; −4.76] cm, respectively" (Corona. 2016). In addition, the provision of testosterone was, as you would probably have guessed based on previous SuppVersity articles, "also associated with a significant reduction in fat and with an increase in lean mass as well as with a reduction in fasting glycemia and insulin resistance" that were accompanied by reductions in fasting glycemia and insulin resistance (IR), as detected by HOMA-IR index - especially in studies enrolling a diabetic subject clientele at baseline (Corona. 2016).

Figure 2: Effects of TRT on blood pressure, lipids and glucose metabolism (Corona. 2016).

But isn't testosterone supplementation (TS) bad for your cholesterol and blood pressure? Even though nobody really appears to care about cholesterol on the interwebs, these days, the claim that testosterone would ruin your blood lipids and, maybe more importantly, one's blood pressure, is still propagated on "the boards". In the studies Corona et al. reviewed for their latest meta-analysis, however, the provision of exogenous testosterone (albeit in not necessarily superphysiological levels) triggered sign. improvements of the subjects' lipid profiles (reduction in total cholesterol as well as of triglyceride levels and an improvement in HDL cholesterol levels) and in both systolic and diastolic blood pressure was observed.

You're scratching your head, I see... Are you disappointed of the effect sizes? Well, you should take a closer look at the full spectrum of the results. Let's take the reduction in waist circumference, for example (Figure 3):

Figure 3: Effect of TS on waist circumference (cm) in the studies that were part of the meta-analysis (Corona. 2016).

As you can see, the latter ranged from ZERO in La Vignera (2009), who didn't even measure the waist circumference ;-) to HERO,... ah, I mean -19.6 cm in Zitzmann (2014), who studied the tolerability and effectiveness of injectable testosterone undecanoate for the treatment of male hypogonadism in a worldwide sample of 1,438 men. With a baseline waist circumference of relatively moderate 99.5 +/ - 15.25 cm, we are talking about a ~20% reduction in waist circumference, here!

Figure 4: Zitzmann et al. also found sign. improvements in mood (left) and the ability to concentrate (right) in their previously (mostly) hypogonodal subjects (Zitzmann, 2014).

Physical changes that were accompanied by significant improvements in the subjects' mood (Figure 4, right) and ability to concentrate (Figure 4, right) - results that had the authors conclude that their "study corroborates and strengthens the modern view on the desirability and efficacy of substitution therapy in men with proven hypogonadism, also in a “real-life” setting" (Zitzmann. 2014).

You to know more about superphysiological doses?

If that's not "good enough" for you, let me remind you of my previous review of a seminal paper by Bhasin et al.  who conducted (to my knowledge) the only "dose-escalation" study that comes remotely close to being a "PED"-RCT, i.e. a controlled trial that may give us some insights into the effects T at dosages that are used by performance enhancing drug users would have.

Figure 5: Dose response relationship of muscle gain (in kg) per mg of testosterone enanthate (left) , the white line indicates a dose that would probably have produce testosterone levels identical to baseline; and relative change in lean and fat mass in response to changes in serum testosterone levels (right | Bhasin. 2001)

While I've reprinted the most important data in Figure 5, I'd still suggest you take a closer look at the corresponding SuppVersity Classic article, if you want to learn more - especially about the interpretation of the graph on the right hand side that shows the relative change in lean and fat mass in response to changes in serum testosterone levels.

Overview of factors controlling muscle gains (Moussa. 2012)

If you want to know what's possible in healthier people, I suggest you go back to my articles in the "Intermittent Thoughts on Building Muscle" series. More specifically, the articles "Zoning in on "The Big T" - Does Testosterone (Alone) Build Muscle?" (read it), "Quan-tifying "The Big T" - Do Testosterone Increases Within the Physiological Range Really Matter? And How Much is too Much?" (read it) and the conclusion "Exercise, mTOR/AKT/MAPK, IGF-1, Testosterone, Estrogen, DHT, Nutrition, Supps & Sleep" (read it) from which I have copied the overview of different mechanism that contribute to / control muscle growth on the right | Comment

References:

• Baker, Julien S., Michael Graham, and Bruce Davies. "Gym users and abuse of prescription drugs." Journal of the Royal Society of Medicine 99.7 (2006a): 331-332.
• Baker, J. S., M. R. Graham, and B. Davies. "Steroid and prescription medicine abuse in the health and fitness community: A regional study." European journal of internal medicine 17.7 (2006b): 479-484.
• Bhasin, Shalender, et al. "Testosterone dose-response relationships in healthy young men." American Journal of Physiology-Endocrinology And Metabolism 281.6 (2001): E1172-E1181.
• Corona, G., et al. "Testosterone supplementation and body composition: results from a meta-analysis of observational studies." Journal of Endocrinological Investigation (2016): 1-15.
• Graham, Michael R., et al. "Anabolic steroid use." Sports medicine 38.6 (2008): 505-525.
• Herschthal, Adam. "From Rats to Riches: How the Anabolic Steroid Control Act of 2004 Unjustly Punished the Gym Rat and How a New Prescription Is the Road to Salvation." Syracuse L. Rev. 63 (2012): 437.
• La Vignera, S., et al. "Andrological characterization of the patient with diabetes mellitus." Minerva endocrinologica 34.1 (2009): 1-9.
• Rahnema, Cyrus D., et al. "Anabolic steroid–induced hypogonadism: diagnosis and treatment." Fertility and sterility 101.5 (2014): 1271-1279.
• Zitzmann, Michael, et al. "IPASS: a study on the tolerability and effectiveness of injectable testosterone undecanoate for the treatment of male hypogonadism in a worldwide sample of 1,438 men." The journal of sexual medicine 10.2 (2013): 579-588.

T-Gel with or Without an Aromatase Inhibitor? If You Are Healthy & Lean and Want to Stay This Way, There is Only One Answer: T-Gel Without Aromatase Inhibitor!

Don't let her talk you into participating in studies that risk your manliness ;-)

Would you be willing to participate in a study, where you could end up without testosterone? No? Well me neither... strangely Joel S. Finkelstein et al. were able to find 198 healthy men between 20 and 50 years who were stupid enough to participate in an experiment, where they were randomized to placebo, or testosterone gel (1.25, 2.5, 5, or 10g per day) while being on gosererelin acetate, which did suppress their natural testosterone production.

With additional 202 subjects receiving an identical "treatment", but in this case alongside a whoppy dose of the aromatase inhibitor anastrazol as a bonus, the study design leaves us with plenty of groups and tons of subjects. To "determine the relative degree of testosterone deficiency, estradiol defi­ciency, or both at which undesirable changes in body composition, strength, and sexual function begin to occur." (Finkelstein 2013)

Yep, that is the study you don't not want to be part of, but....

I bet you will still be interested in the results. Am I right? Ok, let's see then. In men receiving goserelin acetate (kills the natural testosterone production) and 0 g (pla­cebo), 1.25 g, 2.5 g, 5 g, or 10 g of testosterone gel daily (cohort 1), the mean testosterone levels were

• 0g testosterone: 44±13 ng per deciliter, 
• 1.25g testosterone: 191±78 ng per deci­liter
• 2.5g testosterone: 337±173 ng per deciliter, 
• 5g testosterone 470±201 ng per, and
• 10g testosterone 805±355 ng per deciliter

With 1.4 pg per milliliter, 7.9±2.9 pg per mil­liliter, 11.9±5.7 pg per milliliter, 18.2±10.2 pg per milliliter, and 33.3±15.3 pg per milliliter the estrogen levels of all participants were all well within the normal range (<55pg/ml).

Update: As Dr. Crisler (www.allthingsmale.com) just told me the accuracy of the information about estrogen may be questionable, because the essay the scientists used is not reliable in adult men. Instead, he suggest you use a "sensitive" essay like LabCorp (#500108), which uses the "cutting edge" LC/MS technology, Mayo Clinic's "Enhanced Estradiol" (#81816) or LabCorp's "Sensitive Estradiol (#140244), which is less expensive and thus probably a good choice for those without insurance. Dr. Crisler also pointed out that the wide variations you see in T-levels are actually a "very good thing, since this more closely mimics the serum profile of young healthy men". I do not deny that, but I still thought that it was wise to point out that the difference between 805ng/dl and 924ng/dl is absolutely non-significant when you have a range of ±521ng/dl.

Now the latter was obviously true for the guys on the aromatase inhibitor as well, with 1-2pg/ml their levels were however pathologically low and considering the high standard deviations, their T-levels were not that much higher:

Figure 1: Testosterone (ng/dl) and estrogen (pg/ml x10) in healthy men on 0, 1.25, 2.5, 5 and 10g (T0-T10) of testosterone gel with and without an additional aromatase inhibitor (Finkelstein. 2013)

"In men who also received anastrozole (cohort 2), the corresponding mean testosterone levels were 41±13 ng per deciliter, 231±171 ng per deciliter, 367±248 ng per deciliter, 485±240 ng per deci­liter, and 924±521 ng per deciliter and the corresponding mean estradiol levels were 1.0±0.4 pg per milliliter, 1.2±0.4 pg per milliliter, 2.0±2.3 pg per milliliter, 2.1±1.9 pg per millili­ter, and 2.8±1.8 pg per milliliter." (Finkelstein 2003)

[*please note the high (up to 50%!) standard deviations which tell you that the response to transdermal testosterone may vary profoundly from one men to another]

If you take a closer look at the data in Figure 1 and keep in mind that I had to multiply the estrogen levels by x10 in order to fit them into the same graph, it becomes all the more evident that the men in the non-AI group all had normal (<55pg/ml) estrogen levels. Their peers in the anastrazole group, on the other hand, had basically no estrogen at all and correspondingly high testosterone to estrogen ratios. In the worst case (yep, that is something bad!), namely 10g of t-gel + A,I the latter was as high as 335, which is almost 12x higher than in the 2.5g testosterone group without anastrazole (cohort 1).

No T, but tons of body fat

Apropos, cohort 1, in this group of men those who received the anti-androgen goserelin alongside a low(ish) doses of T-gel, i.e. either 0 g, 1.25 g, or 2.5 g of testosterone, daily, had significantly higher body fat levels and those in the 0 and 1.25g of T-gel significantly lower levels of lean mass compared to their peers in the 5g T-gel per day group.

Just a reminder: The testosterone level of the guys in the 5g group was only 470ng/dl and thus still rock bottom - the age adjusted normal levels for men are after all (I highlighted the group, where most of the subjects were in):

• 

  Effects of high and low testosterone on body composition (learn more)

  14-15 yr: 33-585 ng/dL
• 16-17 yr: 185-886 ng/dL
• 18-39 yr: 400-1080 ng/dL
• 40-59 yr: 350-890 ng/dL
• > 60 yr: 350-720 ng/dL

Those on the highest dose of T-gel (10g) ended up at the top (remember the standard deviations) of the normal range for testosterone and right in the happy medium for estrogen (normal range is 14-55pg/ml). These guys  experienced a significant decrease in body fat and increases in tigh muscle area and leg press strength.

Interestingly, both the decrease and increase in body in response to high and low testosterone levels occurred almost exclusively in the "benign" subcutaneous adipose tissue. The intra-abdominal­ fat area, on the other hand did not change significantly in any group. If we follow the standard interpretation of the health effects of the different body fat stores, the conclusion would thus be that low T is not so much of a problem, after all it's all "healthy fat" that you will gain... to bad that too much of that "healthy fat" will make you just as insulin resistance as the visceral fat - it just takes longer for the negative effects to occur.

Now what did the AI do?

Suggested read explaining why the annihilation of E2 has negative effects on your body comp: "Estrogen, Friend or Foe of Muscle Hypertrophy? Plus: Are You 'SERMing' Away Your Satellite Cells?" | more

I know, the most intriguing question has not been answered yet: What was the role of anastrazole in all this? And how did the subjects in cohort 2 fare compared to their "high" (remember even the 10g guys had normal estrogen levels) estrogen counterparts. Well,...

"In cohort 2, the percentage of body fat increased in all groups when the aromatization of testosterone to estradiol was inhibited. The magni­tudes of these increases were similar with doses of 0 g, 1.25 g, 2.5 g, and 5 g of testosterone daily, a finding that suggests a predominantly estro­genic effect" (Finkelstein. 2013)

Yep, I deliberately quoted this, because I know that you've been brain-washed to believe the opposite would happen. The big bad estrogen is what keeps you lean... good that you have been taking natural AIs for years, right? Well, no obviously not. Probably rather the reason that you still don't have the cover-model look you are aspiring.

---

Did you know that (a) the endogenous production of estrogens has significant protective effects on your heard cardiovascular health (Sudhir. 1999) and that (b) aromatase is neuroprotective and low levels of it have been associated with the occurance + progression of neurological diseases such as dementia, Alzheimer's and Parkinsons as well as an inability to recover from mechanic (trauma) or chemical (intlammation) damage to the brain (Azcoitia. 2001)? No? Well, let's hope that this is because you've never heard it and not because you've been abusing AIs for the past decade ;-)

So, to use an AI or not - is that even a question? A direct comparison of all the data from cohort 1 (no aromatase inhibitor) and cohort 2 (using anastrazole), informs us that

"The cohort–testosterone dose interaction was significant for the percentage of body fat (P = 0.001), intraabdominal­fat area (P = 0.021), subcutaneous ­fat area (P = 0.029), sexual desire (P = 0.045), and erectile function (P = 0.032)" (Finkelstein. 2013)

Or, to put it another way: The study shows us that estradiol exerts an inde­pendent effect on body fat, sexual desire and erectile function. So you better don't ignore the real world implications you are about to suffer, when you put too much faith in hearsay instead of looking at your actual blood levels:

"In the groups that received testosterone, inhibi­tion of estrogen synthesis (cohort 2), as com­pared with intact estrogen synthesis (cohort 1), was associated with significant increases in the percentage of body fat (P<0.001), subcutaneous­ fat area (P<0.001), and intraabdominal­fat area (P = 0.002) and with significant decreases in sexual desire (P<0.001) and erectile function (P = 0.022)" (Finkelstein. 2013)

Yes, you heard the scientists right. Suppressing your estrogen levels is going to make you fat, rob you of your sexual desire and render you unable to perform the deed.

At the same time it had no beneficial effect on the increases in lean body mass or strength or any other positive outcome the subjects got from using T-gel. On the contrary, the low estrogen levels on in the 10g T-gel group did actually blunt reduce the lean mass gains and the fat loss the men in cohort 1 (no anastrozole) experienced, when they used 10g of T-gel per day was effectively reversed by the AI.

Figure 2: Fat gain, lower lean mass gain, less sexual desire & lower sexual function (not shown) and the list goes on... there really is nothing remotely beneficial about low estrogen (figures from Finkelstein. 2013).

It should thus be absolutely obvious that the only reason you should use an aromatase inhibitor with your testosterone replacement therapy is blood work that indicates that you have serious issues with over-aromatization. In many cases those can be reduced if not solved by (a) reducing inflammation and (b) getting rid of your belly.

To deliberately annihilate your estrogen levels, on the other hand, is simply stupid - irrespective of whether you are on TRT or not and even if you don't care about the negative long-term effects on your brain and heart health.

References:

• Azcoitia I, Sierra A, Veiga S, Honda S, Harada N, Garcia-Segura LM. Brain aromatase is neuroprotective. J Neurobiol. 2001 Jun 15;47(4):318-29.
• Sudhir K, Komesaroff PA. Clinical review 110: Cardiovascular actions of estrogens in men. J Clin Endocrinol Metab. 1999 Oct;84(10):3411-5. Review.