Nelson Vergel
Founder, ExcelMale.com
Nelson Vergel, reviews a research paper from 2001 by Dr. Bhasin, a leading researcher on testosterone and androgens.
The study looked at the effects of different doses of testosterone on various parameters in young men, including hormones, strength, and sexual function. Key points discussed in the video include:
In conclusion, Vergel mentions the need for further studies to determine optimal testosterone dosage, given the trade-offs in effects on strength, sexual activity, cognition, and cardiovascular risks. He also notes that these results may not generalize to populations that are older, overweight, or physically active.
___________________________
By Nelson Vergel | B.S. Chemical Engineering, MBA | Founder, ExcelMale.com | 34+ years on TRT | NIH and FDA advisory panel service | Author: Testosterone: A Man's Guide, Beyond Testosterone, The Peptide Consensus
Updated July 2026
The numbers below come from two controlled studies where men had their natural testosterone shut off, then received fixed weekly doses under supervision. No gym work was allowed, and diet was standardized. That design is what makes the muscle numbers clean. What you see is testosterone acting on muscle, not testosterone plus a new training program.
Shalender Bhasin's 2001 study is still the clearest map we have. His team took 61 healthy men aged 18 to 35, suppressed their own testosterone with a GnRH agonist, then gave them weekly injections of testosterone enanthate at 25, 50, 125, 300, or 600 mg for 20 weeks. Nobody trained. Diet was controlled. So the muscle changes trace back to dose and nothing else.
Fat-free mass moved in a straight line with dose. The 25 mg group actually lost lean mass, because that dose sits below what a normal man produces. Things turned positive around 50 mg. At 125 mg per week, young men gained roughly 3.4 kg of fat-free mass. At 300 mg it was about 5.2 kg, and at 600 mg about 7.9 kg. Leg press strength climbed alongside testosterone levels. Fat mass fell as the dose rose.
Fat-free mass change over 20 weeks, from Bhasin 2001 (young men) and Bhasin 2005 (older men).
So the honest answer to "how much do you need" depends on your goal. To hold and slowly build lean mass, doses in the 50 to 125 mg range do the job for most men. The 125 mg mark is where the muscle signal gets strong while blood markers stay close to baseline. That is why it keeps coming up as the reference dose in TRT circles.
Yes, and that is exactly the trap. The muscle curve does not flatten out. Men on 600 mg gained more than double the fat-free mass of men on 125 mg. If muscle were the only variable, the answer would be simple: take more.
Blood markers tell the other half of the story. HDL cholesterol dropped as testosterone rose, and hemoglobin climbed right along with it. In the 2001 data these shifts were mild at 125 mg and became clear at 300 and 600 mg. Hematocrit is the marker that forces dose reductions in real practice, because thick blood raises cardiovascular risk and often means donating blood or cutting the dose. HDL moving down is the quieter concern that shows up on a lipid panel months later.
One finding surprised a lot of people. Sexual function, mood, and visual-spatial cognition did not change significantly at any dose. Men expecting libido to scale with milligrams were reading the wrong study. Testosterone builds muscle in a dose-dependent way. It does not fix libido in a dose-dependent way. Those are separate questions, which is why ExcelMale has a whole separate discussion on why testosterone does not always fix low libido.
This is where the second study earns its place. In 2005, Bhasin's group ran the same protocol in men aged 60 to 75 and compared them to the younger cohort. The doses were identical: 25, 50, 125, 300, and 600 mg per week for 20 weeks.
The muscle result was almost a mirror image. Older men gained about -0.3, 1.7, 4.2, 5.6, and 7.3 kg of fat-free mass across the five doses. Line those up next to the young men's numbers and they track closely. The conclusion was direct: older men are as responsive as young men to the anabolic effects of graded doses of testosterone on skeletal muscle. Age does not blunt the muscle response.
The catch is what the same dose does to blood levels. Older men clear testosterone more slowly, so a given milligram dose pushed them to higher serum testosterone than it did the younger men. Hemoglobin rose more in the older group, and the study reported a higher frequency of adverse effects. Same muscle payoff, higher biological cost. If you are over 60 and reading the young-men numbers, subtract some headroom. Your 125 mg is doing more in your bloodstream than a 30-year-old's 125 mg, even though the muscle gain looks the same on the chart.
Because the studies report averages, and you are not an average. This is the point ExcelMale members raise most often when this data comes up, and their experience is worth more than any single mean value.
Gibbon put it plainly: "There is A LOT of room between 50 and 125 mg/wk. 80 mg/wk pushed me into supraphysical and horrible insomnia." Willyt found the same wall even lower: "Years ago I started at usual dose of 100mg per week (split 2 doses) and it wreaked havoc. I have to stay under 50mg per week to avoid side effects." Another member, newuser, reported water bloat and side effects at 75 mg per week.
None of these men are dosing wrong. They metabolize and aromatize testosterone differently. SHBG, aromatase activity, injection frequency, and clearance rate all shift where your personal ceiling sits. A man with low SHBG will have more free testosterone at 80 mg than a man with high SHBG at 120 mg. The Bhasin averages tell you the shape of the curve. They cannot tell you where on that curve your body starts complaining.
Start low and titrate up. That is the consensus that has held on ExcelMale for two decades, and the Bhasin data supports it. If a straight-line dose response means every extra milligram adds muscle and cost, then the smart move is to add milligrams slowly and stop when the cost outpaces the benefit for you.
A workable approach: begin near 100 mg per week, or lower if you have low SHBG or a history of sensitivity. Split the dose into two or more injections to smooth peaks, which helps with water retention and hematocrit. Hold for at least six to eight weeks before judging anything, because levels and symptoms take time to settle. Then check bloodwork before you change the dose, not after side effects show up. The markers that matter for a muscle-focused protocol are total and free testosterone, estradiol, hematocrit, and a lipid panel.
Raise the dose only if muscle progress has stalled and your bloodwork has room. If hematocrit is creeping toward 52 to 54 percent, that is your signal to hold or pull back, not push higher. The men who get in trouble are usually the ones who chased the 300 mg muscle numbers without watching the 300 mg blood numbers.
For most men, 125 mg per week captures a large share of the muscle benefit while keeping hematocrit and HDL close to baseline. In Bhasin's data it produced about 3.4 kg of fat-free mass gain in 20 weeks in young men. Your ideal dose may be lower depending on SHBG, clearance, and how you tolerate it.
Yes. The muscle response is dose-dependent and does not plateau up to 600 mg per week. Men on 600 mg gained roughly 7.9 kg of fat-free mass versus 3.4 kg on 125 mg. The problem is that hematocrit and cardiovascular risk markers rise with the same dose, so more muscle comes with more monitoring and more risk.
Older men build the same amount of muscle at a given dose, but they clear testosterone more slowly and reach higher blood levels and higher hematocrit. Practically, an older man often needs a lower dose to stay in a safe range while still getting a strong muscle response.
Not reliably. Bhasin found that sexual function and mood did not change significantly at any dose, including the high ones. Libido depends on more than testosterone level, which is why some men with good numbers still struggle with it.
Watch hematocrit, HDL, and how you feel. Rising hematocrit toward 52 to 54 percent, dropping HDL, insomnia, and water retention are common signs you have gone past your personal ceiling. Several experienced men feel overdosed below 80 mg per week, so symptoms matter as much as the number on the vial.
One detail that gets lost in the dose charts: the men in these studies had their own testosterone completely shut off first. That is not your situation on TRT. Your protocol has to replace what your body used to make and then decide how much more to add on top for muscle. That baseline is different for every man, which is why two guys on the identical 120 mg protocol can end up with total testosterone levels 400 points apart. Start with the curve, then let your own bloodwork redraw it.
If you want to go deeper on the two levers that most often explain why your dose behaves differently than the chart predicts, read the ExcelMale guides on SHBG and free testosterone and why testosterone does not always fix low libido.
What Is the Optimum TRT Dose for Muscle Growth? Nelson Vergel Reviews the Data. This is the source thread, with the full Bhasin dose-response breakdown and member replies on where their personal side-effect ceiling sits.
Bhasin S, Woodhouse L, Casaburi R, et al. Testosterone dose-response relationships in healthy young men. American Journal of Physiology - Endocrinology and Metabolism. 2001;281(6):E1172-E1181. doi:10.1152/ajpendo.2001.281.6.E1172
Bhasin S, Woodhouse L, Casaburi R, et al. Older men are as responsive as young men to the anabolic effects of graded doses of testosterone on the skeletal muscle. Journal of Clinical Endocrinology & Metabolism. 2005;90(2):678-688. doi:10.1210/jc.2004-1184
Storer TW, Magliano L, Woodhouse L, et al. Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. Journal of Clinical Endocrinology & Metabolism. 2003;88(4):1478-1485. doi:10.1210/jc.2002-021231
Bhasin S, Storer TW, Berman N, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. New England Journal of Medicine. 1996;335(1):1-7. doi:10.1056/NEJM199607043350101
Woodhouse LJ, Gupta N, Bhasin M, et al. Dose-dependent effects of testosterone on regional adipose tissue distribution in healthy young men. Journal of Clinical Endocrinology & Metabolism. 2004;89(2):718-726. doi:10.1210/jc.2003-031492
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715-1744. doi:10.1210/jc.2018-00229
ExcelMale.com is a men's health community with more than 24,000 members and over 20 years of archived discussion on testosterone therapy, hormones, and men's health. It was founded by Nelson Vergel, a chemical engineer with 34+ years on TRT and service on NIH and FDA advisory panels. He is the author of Testosterone: A Man's Guide and Beyond Testosterone.
The study looked at the effects of different doses of testosterone on various parameters in young men, including hormones, strength, and sexual function. Key points discussed in the video include:
- The study involved about 65 healthy young men (average age 25), whose natural testosterone was blocked and were then given varying doses of testosterone cypionate injections (25mg, 50mg, 125mg, 300mg, and 600mg) weekly for 20 weeks.
- The participants were asked not to go to the gym or workout for the study duration to evaluate the effects of the testosterone doses.
- Testosterone levels at baseline were healthy (500s-600s). As the testosterone dose increased, total and free testosterone levels also increased.
- With 125mg per week, the testosterone level was almost back to the baseline. With 300-600mg per week, it went into the 1300s or 2300 nanograms per deciliter.
- As testosterone dose increased, sex hormone binding globulin decreased significantly by 300mg and 600mg doses. IGF-1, a metabolite of growth hormone in the liver, increased significantly at higher doses (300-600mg per week). F
- at-free mass (lean mass and water retention) significantly improved at 125mg or more per week. Fat mass decreased with testosterone, particularly at 125mg or more per week.
- Measurements of thigh muscle volume by MRI showed significant improvement at 125mg and above.
- Sexual activity and intensity of sexual desire did not change significantly across all doses.
- Cognition did not change significantly with any of the doses. Leg press strength and power significantly increased at the 300 and 600mg doses.
- Higher testosterone doses increased hemoglobin and red blood cells but decreased HDL (good cholesterol).
In conclusion, Vergel mentions the need for further studies to determine optimal testosterone dosage, given the trade-offs in effects on strength, sexual activity, cognition, and cardiovascular risks. He also notes that these results may not generalize to populations that are older, overweight, or physically active.
___________________________
By Nelson Vergel | B.S. Chemical Engineering, MBA | Founder, ExcelMale.com | 34+ years on TRT | NIH and FDA advisory panel service | Author: Testosterone: A Man's Guide, Beyond Testosterone, The Peptide Consensus
Updated July 2026
The numbers below come from two controlled studies where men had their natural testosterone shut off, then received fixed weekly doses under supervision. No gym work was allowed, and diet was standardized. That design is what makes the muscle numbers clean. What you see is testosterone acting on muscle, not testosterone plus a new training program.
How Much Testosterone Do You Actually Need to Build Muscle?
Shalender Bhasin's 2001 study is still the clearest map we have. His team took 61 healthy men aged 18 to 35, suppressed their own testosterone with a GnRH agonist, then gave them weekly injections of testosterone enanthate at 25, 50, 125, 300, or 600 mg for 20 weeks. Nobody trained. Diet was controlled. So the muscle changes trace back to dose and nothing else.
Fat-free mass moved in a straight line with dose. The 25 mg group actually lost lean mass, because that dose sits below what a normal man produces. Things turned positive around 50 mg. At 125 mg per week, young men gained roughly 3.4 kg of fat-free mass. At 300 mg it was about 5.2 kg, and at 600 mg about 7.9 kg. Leg press strength climbed alongside testosterone levels. Fat mass fell as the dose rose.
| Weekly Dose | Fat-Free Mass (young men) | Fat-Free Mass (older men) |
|---|---|---|
| 25 mg | -1.0 kg | -0.3 kg |
| 50 mg | +1.0 kg | +1.7 kg |
| 125 mg | +3.4 kg | +4.2 kg |
| 300 mg | +5.2 kg | +5.6 kg |
| 600 mg | +7.9 kg | +7.3 kg |
Fat-free mass change over 20 weeks, from Bhasin 2001 (young men) and Bhasin 2005 (older men).
So the honest answer to "how much do you need" depends on your goal. To hold and slowly build lean mass, doses in the 50 to 125 mg range do the job for most men. The 125 mg mark is where the muscle signal gets strong while blood markers stay close to baseline. That is why it keeps coming up as the reference dose in TRT circles.
Does the Muscle Benefit Keep Rising With Higher Doses?
Yes, and that is exactly the trap. The muscle curve does not flatten out. Men on 600 mg gained more than double the fat-free mass of men on 125 mg. If muscle were the only variable, the answer would be simple: take more.
Blood markers tell the other half of the story. HDL cholesterol dropped as testosterone rose, and hemoglobin climbed right along with it. In the 2001 data these shifts were mild at 125 mg and became clear at 300 and 600 mg. Hematocrit is the marker that forces dose reductions in real practice, because thick blood raises cardiovascular risk and often means donating blood or cutting the dose. HDL moving down is the quieter concern that shows up on a lipid panel months later.
One finding surprised a lot of people. Sexual function, mood, and visual-spatial cognition did not change significantly at any dose. Men expecting libido to scale with milligrams were reading the wrong study. Testosterone builds muscle in a dose-dependent way. It does not fix libido in a dose-dependent way. Those are separate questions, which is why ExcelMale has a whole separate discussion on why testosterone does not always fix low libido.
Do Older Men Respond to Testosterone Differently Than Young Men?
This is where the second study earns its place. In 2005, Bhasin's group ran the same protocol in men aged 60 to 75 and compared them to the younger cohort. The doses were identical: 25, 50, 125, 300, and 600 mg per week for 20 weeks.
The muscle result was almost a mirror image. Older men gained about -0.3, 1.7, 4.2, 5.6, and 7.3 kg of fat-free mass across the five doses. Line those up next to the young men's numbers and they track closely. The conclusion was direct: older men are as responsive as young men to the anabolic effects of graded doses of testosterone on skeletal muscle. Age does not blunt the muscle response.
The catch is what the same dose does to blood levels. Older men clear testosterone more slowly, so a given milligram dose pushed them to higher serum testosterone than it did the younger men. Hemoglobin rose more in the older group, and the study reported a higher frequency of adverse effects. Same muscle payoff, higher biological cost. If you are over 60 and reading the young-men numbers, subtract some headroom. Your 125 mg is doing more in your bloodstream than a 30-year-old's 125 mg, even though the muscle gain looks the same on the chart.
Why Do Some Men Get Side Effects at Doses Far Below 125 mg?
Because the studies report averages, and you are not an average. This is the point ExcelMale members raise most often when this data comes up, and their experience is worth more than any single mean value.
Gibbon put it plainly: "There is A LOT of room between 50 and 125 mg/wk. 80 mg/wk pushed me into supraphysical and horrible insomnia." Willyt found the same wall even lower: "Years ago I started at usual dose of 100mg per week (split 2 doses) and it wreaked havoc. I have to stay under 50mg per week to avoid side effects." Another member, newuser, reported water bloat and side effects at 75 mg per week.
None of these men are dosing wrong. They metabolize and aromatize testosterone differently. SHBG, aromatase activity, injection frequency, and clearance rate all shift where your personal ceiling sits. A man with low SHBG will have more free testosterone at 80 mg than a man with high SHBG at 120 mg. The Bhasin averages tell you the shape of the curve. They cannot tell you where on that curve your body starts complaining.
How Should You Find Your Own Dose for Muscle Growth?
Start low and titrate up. That is the consensus that has held on ExcelMale for two decades, and the Bhasin data supports it. If a straight-line dose response means every extra milligram adds muscle and cost, then the smart move is to add milligrams slowly and stop when the cost outpaces the benefit for you.
A workable approach: begin near 100 mg per week, or lower if you have low SHBG or a history of sensitivity. Split the dose into two or more injections to smooth peaks, which helps with water retention and hematocrit. Hold for at least six to eight weeks before judging anything, because levels and symptoms take time to settle. Then check bloodwork before you change the dose, not after side effects show up. The markers that matter for a muscle-focused protocol are total and free testosterone, estradiol, hematocrit, and a lipid panel.
Raise the dose only if muscle progress has stalled and your bloodwork has room. If hematocrit is creeping toward 52 to 54 percent, that is your signal to hold or pull back, not push higher. The men who get in trouble are usually the ones who chased the 300 mg muscle numbers without watching the 300 mg blood numbers.
Frequently Asked Questions
What is the best testosterone dose for building muscle on TRT?
For most men, 125 mg per week captures a large share of the muscle benefit while keeping hematocrit and HDL close to baseline. In Bhasin's data it produced about 3.4 kg of fat-free mass gain in 20 weeks in young men. Your ideal dose may be lower depending on SHBG, clearance, and how you tolerate it.
Does a higher testosterone dose build more muscle?
Yes. The muscle response is dose-dependent and does not plateau up to 600 mg per week. Men on 600 mg gained roughly 7.9 kg of fat-free mass versus 3.4 kg on 125 mg. The problem is that hematocrit and cardiovascular risk markers rise with the same dose, so more muscle comes with more monitoring and more risk.
Do older men need a different testosterone dose than younger men?
Older men build the same amount of muscle at a given dose, but they clear testosterone more slowly and reach higher blood levels and higher hematocrit. Practically, an older man often needs a lower dose to stay in a safe range while still getting a strong muscle response.
Will 125 mg of testosterone per week increase my libido?
Not reliably. Bhasin found that sexual function and mood did not change significantly at any dose, including the high ones. Libido depends on more than testosterone level, which is why some men with good numbers still struggle with it.
How do I know if my testosterone dose is too high?
Watch hematocrit, HDL, and how you feel. Rising hematocrit toward 52 to 54 percent, dropping HDL, insomnia, and water retention are common signs you have gone past your personal ceiling. Several experienced men feel overdosed below 80 mg per week, so symptoms matter as much as the number on the vial.
Conclusion
One detail that gets lost in the dose charts: the men in these studies had their own testosterone completely shut off first. That is not your situation on TRT. Your protocol has to replace what your body used to make and then decide how much more to add on top for muscle. That baseline is different for every man, which is why two guys on the identical 120 mg protocol can end up with total testosterone levels 400 points apart. Start with the curve, then let your own bloodwork redraw it.
If you want to go deeper on the two levers that most often explain why your dose behaves differently than the chart predicts, read the ExcelMale guides on SHBG and free testosterone and why testosterone does not always fix low libido.
Related ExcelMale Forum Discussions
What Is the Optimum TRT Dose for Muscle Growth? Nelson Vergel Reviews the Data. This is the source thread, with the full Bhasin dose-response breakdown and member replies on where their personal side-effect ceiling sits.
Key References
Bhasin S, Woodhouse L, Casaburi R, et al. Testosterone dose-response relationships in healthy young men. American Journal of Physiology - Endocrinology and Metabolism. 2001;281(6):E1172-E1181. doi:10.1152/ajpendo.2001.281.6.E1172
Bhasin S, Woodhouse L, Casaburi R, et al. Older men are as responsive as young men to the anabolic effects of graded doses of testosterone on the skeletal muscle. Journal of Clinical Endocrinology & Metabolism. 2005;90(2):678-688. doi:10.1210/jc.2004-1184
Storer TW, Magliano L, Woodhouse L, et al. Testosterone dose-dependently increases maximal voluntary strength and leg power, but does not affect fatigability or specific tension. Journal of Clinical Endocrinology & Metabolism. 2003;88(4):1478-1485. doi:10.1210/jc.2002-021231
Bhasin S, Storer TW, Berman N, et al. The effects of supraphysiologic doses of testosterone on muscle size and strength in normal men. New England Journal of Medicine. 1996;335(1):1-7. doi:10.1056/NEJM199607043350101
Woodhouse LJ, Gupta N, Bhasin M, et al. Dose-dependent effects of testosterone on regional adipose tissue distribution in healthy young men. Journal of Clinical Endocrinology & Metabolism. 2004;89(2):718-726. doi:10.1210/jc.2003-031492
Bhasin S, Brito JP, Cunningham GR, et al. Testosterone therapy in men with hypogonadism: an Endocrine Society clinical practice guideline. Journal of Clinical Endocrinology & Metabolism. 2018;103(5):1715-1744. doi:10.1210/jc.2018-00229
Medical Disclaimer
About ExcelMale
ExcelMale.com is a men's health community with more than 24,000 members and over 20 years of archived discussion on testosterone therapy, hormones, and men's health. It was founded by Nelson Vergel, a chemical engineer with 34+ years on TRT and service on NIH and FDA advisory panels. He is the author of Testosterone: A Man's Guide and Beyond Testosterone.
Last edited:
