Barbell Medicine Podcast

Most cases of low testosterone in modern men are not a problem with the testes. The number is downstream of body composition, sleep, and energy availability. The wellness-clinic algorithm walks past every one of them.

Jordan and Austin walk through what actually drives men’s testosterone down, the mechanisms behind it, and the modifiable levers that bring it back up. MOSH, the leptin and Kisspeptin pathway, the aromatase loop, the sleep apnea picture most clinics never ask about, the GLP-1 and weight-loss data on testosterone recovery, the low energy availability case that hits high-volume lifters harder than they realize, and the closing question of when a standard-dose TRT prescription actually functions as a PED.
This is Episode 3 of our four-part Signal book launch series. Mark, the patient we have been threading from Episode 1, finally gets his diagnosis revealed.
Timestamps
00:00 The 9x stat and Mark's diagnosis revealed
 02:10 How body fat suppresses testosterone (MOSH)
 07:26 Primary vs secondary causes, and Klinefelter
 11:35 Leptin and the Kisspeptin pathway
 14:38 Mark: the body-composition picture
 16:10 The 40-inch-waist case
 20:01 Weight loss, GLP-1s, and does Ozempic raise testosterone?
 24:21 T4DM: adding testosterone to lifestyle
 28:35 Sleep, OSA, and Mark's diagnosis
 38:39 TRT in untreated sleep apnea
 41:47 Can you train your testosterone down? (LEA / EHMC)
 50:12 Replacement dose vs PED
 55:47 Four takeaways
 57:46 Episode 4 preview and book pre-order

What we cover:
•         How body fat suppresses testosterone at two different points in the HPG axis, and why the loop is self-reinforcing
•         The leptin and Kisspeptin pathway most clinics never address
•         Mark’s case: a 45-year-old with a 240 ng/dL afternoon draw, no workup, and an immediate prescription
•         Primary versus secondary causes, and why Klinefelter syndrome is the under-recognized one to not miss
•         Weight loss dose-response: how much testosterone climbs on lifestyle alone, with GLP-1 agonists, and after bariatric surgery
•         T4DM: why adding testosterone to a structured weight-loss program produced no extra quality-of-life benefit over placebo
•         One week of sleep restriction drops testosterone by about 15 percent in healthy young men; eight days of military field exercises drop it by 50 percent
•         Why CPAP for obstructive sleep apnea reliably improves symptoms but does not always move the lab number
•         The opposite extreme: low energy availability, relative energy deficiency in sport, and the exercise-hypogonadal male condition
•         The lifter calculus: when a textbook replacement dose is functionally a PED in a chronically underfueled trainee

Resources mentioned:
Signal book pre-order: https://barbellmedicine.com/signal
 Training Plateau Action Plan (free): https://www.barbellmedicine.com/training-plateau-action-plan/
 Barbell Medicine programs and coaching: https://www.barbellmedicine.com/
 Episode 1 (Is the Testosterone Crisis Real?)
 Episode 2 (Is Your Testosterone Actually Low?

Referenced studies:

Wu F.C.W. et al. 2010. Identification of late-onset hypogonadism in middle-aged and elderly men (EMAS). N Engl J Med 363(2):123-135.
 https://pubmed.ncbi.nlm.nih.gov/20554979/
 
 Travison T.G. et al. 2011. The natural history of symptomatic androgen deficiency in men. J Am Geriatr Soc.
 https://pubmed.ncbi.nlm.nih.gov/18454751/
 
 Corona G. et al. 2013. Body weight loss reverts obesity-associated hypogonadotropic hypogonadism: systematic review and meta-analysis. Eur J Endocrinol 168(6):829-843.
 https://pubmed.ncbi.nlm.nih.gov/23482592/
 
 Kounatidis D. et al. 2025. The impact of GLP-1 receptor agonists on erectile function. Biomolecules 15(9):1284.
 https://doi.org/10.3390/biom15091284
 
 Grossmann M. et al. 2024. Testosterone treatment, weight loss, and health-related quality of life and psychosocial function in men: 2-year RCT (T4DM QoL arm). J Clin Endocrinol Metab 109(8):2019-2028.
 https://pubmed.ncbi.nlm.nih.gov/38311835/
 
 Leproult R., Van Cauter E. 2011. Effect of 1 week of sleep restriction on testosterone levels in young healthy men. JAMA 305(21):2173-2174.
 https://pubmed.ncbi.nlm.nih.gov/21632481/
 
 Penev P.D. 2007. Association between sleep and morning testosterone levels in older men. Sleep 30(4):427-432.
 https://pubmed.ncbi.nlm.nih.gov/17520785/
 
 Wittert G. 2014. The relationship between sleep disorders and testosterone in men. Asian J Androl 16(2):262-265.
 https://pubmed.ncbi.nlm.nih.gov/24435056/
 
 Alemany J.A. et al. 2008. Effects of dietary protein content on IGF-I, testosterone, and body composition during 8 days of severe energy deficit and arduous physical activity. J Appl Physiol 105(1):58-64.
 https://pubmed.ncbi.nlm.nih.gov/18450989/
 
 Mountjoy M., Sundgot-Borgen J.K., Burke L.M. et al. 2018. IOC consensus statement on relative energy deficiency in sport (RED-S): 2018 update. Br J Sports Med 52:687-697.
 https://pubmed.ncbi.nlm.nih.gov/29773536/
 
 Areta J.L. et al. 2021. Low energy availability: history, definition and evidence of its endocrine, metabolic and physiological effects in prospective studies in females and males. Eur J Appl Physiol 121(1):1-21.
 https://pubmed.ncbi.nlm.nih.gov/33095376/
 
 Mäestu J. et al. 2010. Anabolic and catabolic hormones and energy balance of the male bodybuilders during the preparation for the competition. J Strength Cond Res 24(4):1074-1081.
 https://pubmed.ncbi.nlm.nih.gov/20300023/
 
 Hooper D.R. et al. 2018. Treating exercise-associated low testosterone (EHMC). Phys Sportsmed 46(4):427-434.
 https://pubmed.ncbi.nlm.nih.gov/30074435/
 
 Hackney A.C. 2020. Hypogonadism in exercising males: dysfunction or adaptive-regulatory adjustment? Front Endocrinol 11:11.
 https://pubmed.ncbi.nlm.nih.gov/32082252/

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Three weeks of stalled squats. The conventional answer is to switch programs because you've crossed into intermediate territory. The data says something else. In Part 3 of the Progressive Loading series, Dr. Jordan Feigenbaum and Dr. Austin Baraki walk through why the standard novice / intermediate / advanced framework runs into trouble in real training, what the four adaptive systems are actually doing across a training career, and why most of what gets called a stall is impatience with the noise floor at your current strength level.
This is Part 3 of the Progressive Loading series. Part 1 covered why loading should react to demonstrated adaptation. Part 2 covered RPE-based autoregulation and the artificial-momentum approach. Today is the mechanism layer.
Pre-order our book, Signal: barbellmedicine.com/signal
Timestamps
0:00 - Why your lifts aren't moving
1:52 - The novice / intermediate / advanced framework, three claims to test
13:23 - What 17 years of powerlifting data show about how long you keep getting stronger
32:28 - How getting stronger actually works (four systems on four clocks)
38:00 - What early growth is actually made of (the Damas 2016 deuterium study)
50:33 - The connective tissue lag and why early-training injuries happen
58:32 - Why heavy lifting works for bone density (and why "walk on a treadmill" advice misses)
1:05:10 - Why new lifters get hurt 3 to 10 times more than experienced lifters
1:12:56 - Fatigue is at least four different things (and most coaches treat it as one)
1:26:19 - The CNS fatigue myth (and what the data actually says)
1:33:52 - When the bar isn't moving: how to actually diagnose a stall
1:45:51 - Takeaways and next week's tease: leptin and low testosterone

What we cover 
- The novice / intermediate / advanced framework: three claims and why each one fails the data test
- The 17-year IPF strength curve and what the no-kink finding does and does not establish (Latella 2024)
- The four adaptive systems and their separate timescales (neural, muscle, connective tissue, bone)
- What early growth actually is, including the deuterium-oxide finding that most week-3 size is fluid (Damas 2016)
- Why connective tissue lags muscle by six to eight weeks, and why that produces patellar tendinopathy four months in
- The 9.5 vs 0.74 to 3.3 injury rate gap between novice and experienced CrossFit participants
- The CNS fatigue myth and the Skarabot 2018 finding that locates the fatigue in the muscle, not the brain
- Why the LIFTMOR trial result (heavy lifting for bone density in women in their 60s and 70s) is being missed by primary care
- A practical decision tree for stalls: environment first, then load, then program
- Tease for next week: leptin, the HPG axis, and the metabolic driver of low testosterone almost nobody connects

Resources 
Training Plateau Action Plan (free): https://www.barbellmedicine.com/training-plateau-action-plan/
Progressive Loading article series: https://www.barbellmedicine.com/blog/progressive-loading/
Beyond Progressive Overload (Part 2 article): https://www.barbellmedicine.com/blog/beyond-progressive-overload/
BBM Programs and Coaching: https://www.barbellmedicine.com/
Support our work on barbellmedicine.supercast.com
Latella C et al. Using powerlifting athletes to determine strength adaptations across ages in males and females. Sports Med. 2024. https://pubmed.ncbi.nlm.nih.gov/

Del Vecchio A et al. The increase in muscle force after 4 weeks of strength training is mediated by adaptations in motor unit recruitment and rate coding. J Physiol. 2019. https://pubmed.ncbi.nlm.nih.gov/30644584/

Lecce E et al. Resistance training-induced adaptations in the neuromuscular system. J Physiol. 2025.

Balshaw TG et al. Neural adaptations after 4 years vs 12 weeks of resistance training. Scand J Med Sci Sports. 2019. https://pubmed.ncbi.nlm.nih.gov/30474171/

Skarabot J et al. Voluntary activation and agonist EMG amplitude in resistance-trained men. J Appl Physiol. 2021.

Roberts MD et al. Mechanisms of mechanical overload-induced skeletal muscle hypertrophy. Physiol Rev. 2023.

Damas F et al. Resistance training-induced changes in integrated myofibrillar protein synthesis are related to hypertrophy only after attenuation of muscle damage. J Physiol. 2016. https://pubmed.ncbi.nlm.nih.gov/27219125/

Damas F et al. Early resistance training-induced increases in muscle cross-sectional area are concomitant with edema-induced muscle swelling. Eur J Appl Physiol. 2016. https://pubmed.ncbi.nlm.nih.gov/26280652/

Lazarczuk SL et al. Mechanical, material and morphological adaptations of healthy lower limb tendons. Sports Med. 2022. https://pubmed.ncbi.nlm.nih.gov/35657492/

Kubo K et al. Time course of changes in the human Achilles tendon properties. Eur J Appl Physiol. 2012. https://pubmed.ncbi.nlm.nih.gov/22105708/

Watson SL et al. High-intensity resistance and impact training improves bone mineral density in postmenopausal women: the LIFTMOR randomized controlled trial. J Bone Miner Res. 2018. https://pubmed.ncbi.nlm.nih.gov/28975661/

Aasa U et al. Injuries among weightlifters and powerlifters: a systematic review. Br J Sports Med. 2017. https://pubmed.ncbi.nlm.nih.gov/27445362/

Prieto-Gonzalez P et al. Injuries in novice participants during an eight-week start-up CrossFit program. Int J Environ Res Public Health. 2020. https://pubmed.ncbi.nlm.nih.gov/32155747/

Kanayama G et al. Tendon rupture in body builders. Sports Med. 2015.

Enoka RM, Duchateau J. Translating fatigue to human performance. Med Sci Sports Exerc. 2016. https://pubmed.ncbi.nlm.nih.gov/27015386/

Behrens M et al. Fatigue and human performance: an updated framework. Sports Med. 2023. https://pubmed.ncbi.nlm.nih.gov/

Halperin I et al. Accuracy in predicting repetitions to task failure: scoping review. Sports Med. 2022. https://pubmed.ncbi.nlm.nih.gov/

Skarabot J et al. Neuromuscular fatigue and recovery after heavy resistance, jump, and sprint training. Eur J Appl Physiol. 2018.

Garcia-Ramos A et al. Greater neuromuscular and perceptual fatigue after low-load to failure than heavy-load to failure. 2024.

Minor, Brian MS, CSCS1; Helms, Eric PhD, CSCS2; Schepis, Jacob3. RE: Mesocycle Progression in Hypertrophy: Volume Versus Intensity. Strength and Conditioning Journal 42(5):p 121-124, October 2020. | DOI: 10.1519/SSC.0000000000000581

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Out of 32 symptoms commonly attributed to low testosterone, only 3 actually correlate with it. All three are sexual. The other 29 — fatigue, brain fog, low mood, weight you can't lose, feeling not quite like yourself — are real, but they are produced by something else, and the wellness-clinic funnel runs on getting that wrong.
 
Episode 2 of our Signal book launch series. Dr. Jordan Feigenbaum and Dr. Austin Baraki cover how testosterone actually works, what the number on your lab report is really measuring, and what a real evaluation of low T looks like.

Pre-order our book, Signal: barbellmedicine.com/signal

Timestamps:
00:00 Mark, revisited (cold open)
02:00 How testosterone actually works (HPG axis)
06:14 Why "in range" can still be abnormal
09:24 What your lab number actually measures
12:25 Case: total 230, low SHBG — does this guy need TRT?
17:04 The saturation model — why higher isn't better
21:11 A patient at 480 wants 900: how the conversation goes
28:57 What "in range" actually means (and why 264 is the cutoff)
34:41 The 3 symptoms that matter (out of 32)
37:16 Walking back a 10-symptom checklist
42:31 How a real testosterone workup gets done
46:42 Chasland trial — TRT vs. exercise at low-normal T
49:31 A warning for hard-training men
58:48 Takeaways, tease, and what's coming next 
What we cover:
The HPG axis explained — and why one low total testosterone reading tells you almost nothing about where the problem actually sits.
The difference between total, free, and bioavailable testosterone — and why SHBG, the binding protein the wellness-clinic workup almost always ignores, is what determines whether the number on your lab report is misleading you in either direction.
The saturation model: above roughly 250 ng/dL, the prostate androgen receptor is saturated. Libido follows the same plateau. Pushing a normal man from 500 to 900 isn't doing what the marketing implies.
The EMAS study finding: of 32 symptoms men commonly attribute to low testosterone, only 3 actually correlate. Every other symptom needs a different workup.
How a real testosterone workup gets done — morning sample, fasted, repeat draw, LH/FSH/SHBG to localize and contextualize.
The Chasland 2021 trial: when standard TRT is prescribed properly to middle-aged men with low-normal levels, does it beat exercise? The answer is what most of the wellness-clinic industry is built on getting wrong.
A note for hard-training men: the exercise-hypogonadal-male pattern, what "low-normal" means in someone whose levels are an adaptation to training load rather than a baseline deficit, and why a textbook TRT dose in that man may functionally act as a performance enhancer.
If you have a lab report on your kitchen counter right now, this is what we wrote for you. Signal, the book, drops in May. Pre-order available soon at barbellmedicine.com.

Resources & links
Signal — Feigenbaum & Baraki (Barbell Medicine, 2026): coming soon
Episode 1 (Is the Testosterone Crisis Real?): https://stream.redcircle.com/episodes/b25a8006-57e5-4dc3-b74c-203f6fbcebc1/stream.mp3
Training Plateau Action Plan (free): barbellmedicine.com/training-plateau-action-plan
Barbell Medicine programs and consultations: barbellmedicine.com
To support us and get ad free listening, plus special product discounts, and exclusive content, go to supercast.barbellmedicine.com

Referenced studies
Wu FCW et al. 2010 - Identification of late-onset hypogonadism in middle-aged and elderly men. NEJM 363(2):123-135. [The EMAS 3-of-32 finding]
https://pubmed.ncbi.nlm.nih.gov/20554979/

Bhasin S et al. 2018 - Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. JCEM 103(5):1715-1744. [264 ng/dL threshold; first-draw protocol]
https://pubmed.ncbi.nlm.nih.gov/29562364/

Travison TG et al. 2008 - The natural history of symptomatic androgen deficiency in men. JAGS 56(5):831-839. [MMAS: ~50% of initially low values normalize on repeat]
https://pubmed.ncbi.nlm.nih.gov/18308002/

Travison TG et al. 2006 - The relationship between libido and testosterone levels in aging men. JCEM 91(7):2509-2513. [Libido plateau data, Framingham + HIM]
https://pubmed.ncbi.nlm.nih.gov/16670164/

Brambilla DJ et al. 2009 - The effect of diurnal variation on clinical measurement of serum testosterone. JCEM 94(3):907-913. [Why morning, fasted matters]
https://pubmed.ncbi.nlm.nih.gov/19112025/

Morgentaler A & Traish AM. 2009 - Shifting the paradigm of testosterone and prostate cancer: the saturation model and the limits of androgen-dependent growth. Eur Urol 55(2):310-320. [The saturation model]
https://pubmed.ncbi.nlm.nih.gov/18838208/

Trost LW & Mulhall JP. 2016 - Challenges in Testosterone Measurement, Data Interpretation, and Methodological Appraisal of Interventional Trials. J Sex Med 13(7):1029-1046. [Free T unreliability at the low end; equilibrium dialysis as the reference method]
https://pubmed.ncbi.nlm.nih.gov/27210182/

Vermeulen A et al. 1999 - A critical evaluation of simple methods for the estimation of free testosterone in serum. JCEM 84(10):3666-3672. [Calculated free T methodology]
https://pubmed.ncbi.nlm.nih.gov/10523012/

Chasland LC et al. 2021 - Testosterone and exercise: effects on fitness, body composition, and strength in middle-to-older aged men with low-normal serum testosterone levels. Am J Physiol Heart Circ Physiol 320(5):H1985-H1998. [The 12-week trial]
https://pubmed.ncbi.nlm.nih.gov/33739153/

Arun AS et al. 2025 - Reevaluating the Threshold for Low Total Testosterone. Clin Chem 71(5):609-611. [2025 NHANES strength-dissociation reference]
https://pubmed.ncbi.nlm.nih.gov/40066943/

Baillargeon J et al. 2015 - Trends in Androgen Prescribing in the United States, 2001-2011. JAMA Intern Med 175(8):1413-1415. [25% no preceding lab; the 50% no follow-up monitoring gap - referenced from Episode 1]
https://pubmed.ncbi.nlm.nih.gov/26075486/

Our Sponsors:
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Stop a GLP-1 and about two thirds of the weight loss comes back within a year. Three randomized withdrawal trials (SURMOUNT-4, STEP 1 extension, STEP 4) and a new BMJ 2026 systematic review of 37 RCTs and nearly 10,000 adults all land on the same signal. The cardiometabolic benefits, blood pressure, fasting glucose, lipids, drift back in parallel with the weight. The framing that actually fits the data: GLP-1s behave like a statin. There is a cumulative benefit during exposure, but this does not extend indefinitely,
This month's Direct Line covers two subscriber questions. The first asks what the new BMJ paper on GLP-1 cardiovascular protection after cessation actually shows, and how GLP-1 durability compares to lifestyle-only interventions. The second asks how a postmenopausal woman newly diagnosed with osteopenia should structure her lifting.
Studies referenced: SURMOUNT-4 (Jastreboff, JAMA 2024), STEP 1 extension (Wilding, Diabetes Obes Metab 2022), STEP 4 (Rubino, JAMA 2021), West et al. BMJ 2026 systematic review, Budini 2026 eClinicalMedicine regain meta-analysis, SELECT cardiovascular outcomes, FLOW renal outcomes, the Diabetes Prevention Program, Look AHEAD, POUNDS Lost, and LIFTMOR (Watson, JBMR 2018).
Full episode on BBM+ covers 8 additional subscriber questions. Join at https://barbellmedicine.supercast.com/
Timestamps
0:00 Intro
1:52 Q1: What happens when you stop a GLP-1
5:33 Lifestyle-only comparators: DPP, Look AHEAD, POUNDS Lost
8:15 Austin on the cessation conversation 1
2:41 BMJ 2026: weight and cardiometabolic regression
17:59 The statin framing
23:41 Austin: first 6 months off GLP-1
28:07 Q2: Osteopenia and heavy lifting
35:28 LIFTMOR protocol
38:00 Outro

Next Steps
For evidence-based resistance training programs: barbellmedicine.com/training-programs
For individualized training consultation: barbellmedicine.com/coaching
Explore our full library of articles on health and performance: barbellmedicine.com/resources
To consult with Drs. Baraki or Feigenbaum email us at [email protected]

Resources
Aronne, Louis J., et al. "Continued Treatment With Tirzepatide for Maintenance of Weight Reduction in Adults With Obesity: The SURMOUNT-4 Randomized Clinical Trial." JAMA, vol. 331, no. 1, 2024, pp. 38–48. https://jamanetwork.com/journals/jama/fullarticle/2812936
Wilding, John P. H., et al. "Weight Regain and Cardiometabolic Effects After Withdrawal of Semaglutide: The STEP 1 Trial Extension." Diabetes, Obesity and Metabolism, vol. 24, no. 8, Aug. 2022, pp. 1553–1564. https://dom-pubs.onlinelibrary.wiley.com/doi/10.1111/dom.14725
Rubino, Domenica, et al. "Effect of Continued Weekly Subcutaneous Semaglutide vs Placebo on Weight Loss Maintenance in Adults With Overweight or Obesity: The STEP 4 Randomized Clinical Trial." JAMA, vol. 325, no. 14, 2021, pp. 1414–1425. https://jamanetwork.com/journals/jama/fullarticle/2777886
West, Sam, et al. "Weight Regain After Cessation of Medication for Weight Management: Systematic Review and Meta-Analysis." BMJ, vol. 392, 7 Jan. 2026, article e085304. https://www.bmj.com/content/392/bmj-2025-085304
Budini, Brajan, et al. "Trajectory of Weight Regain After Cessation of GLP-1 Receptor Agonists: A Systematic Review and Nonlinear Meta-Regression." eClinicalMedicine, vol. 93, 4 Mar. 2026, article 103796. https://www.thelancet.com/journals/eclinm/article/PIIS2589-5370(26)00043-X/fulltext
Lincoff, A. Michael, et al. "Semaglutide and Cardiovascular Outcomes in Obesity Without Diabetes." New England Journal of Medicine, vol. 389, no. 24, 11 Nov. 2023, pp. 2221–2232. https://www.nejm.org/doi/full/10.1056/NEJMoa2307563
Perkovic, Vlado, et al. "Effects of Semaglutide on Chronic Kidney Disease in Patients with Type 2 Diabetes." New England Journal of Medicine, vol. 391, no. 2, 24 May 2024, pp. 109–121. https://www.nejm.org/doi/full/10.1056/NEJMoa2403347
Knowler, William C., et al. "Reduction in the Incidence of Type 2 Diabetes with Lifestyle Intervention or Metformin." New England Journal of Medicine, vol. 346, no. 6, 7 Feb. 2002, pp. 393–403. https://www.nejm.org/doi/full/10.1056/NEJMoa012512
Look AHEAD Research Group. "Cardiovascular Effects of Intensive Lifestyle Intervention in Type 2 Diabetes." New England Journal of Medicine, vol. 369, no. 2, 11 July 2013, pp. 145–154. https://www.nejm.org/doi/full/10.1056/NEJMoa1212914
Sacks, Frank M., et al. "Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates." New England Journal of Medicine, vol. 360, no. 9, 26 Feb. 2009, pp. 859–873. https://www.nejm.org/doi/full/10.1056/NEJMoa0804748
Watson, Shelley L., et al. "High-Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmenopausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial." Journal of Bone and Mineral Research, vol. 33, no. 2, 2018, pp. 211–220. https://onlinelibrary.wiley.com/doi/10.1002/jbmr.3284

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Every week there's a new headline saying men are losing testosterone. A quarter of men now start testosterone replacement therapy without ever getting their blood tested. The supplement aisle is full of boosters that either do nothing or contain undisclosed steroids. And the lab test that gets everybody to the pharmacy? Half of low results normalize on their own.
In Episode 1 of the Signal launch series, Dr. Jordan Feigenbaum and Dr. Austin Baraki (both MDs and strength coaches) walk through the three-layer problem with how testosterone gets diagnosed and treated in 2026, then take apart the "testosterone is crashing" headline with the most current data available, including a 2025 meta-analysis of more than one million men.
Pre-order our book, Signal: barbellmedicine.com/signal

Timestamps
0:00 Mark's story: treating the number, not the patient
1:18 Welcome to the Barbell Medicine Podcast
1:41 Problem 1: A quarter of men start TRT with no lab work
3:36 Problem 2: Why testosterone boosters do not work (and what is in them)
13:40 Problem 3: Why one low testosterone lab is not a diagnosis
19:19 Setup: Is the testosterone crisis headline real?
20:04 The MMAS data and the 1%-per-year number
20:52 The 2025 meta-analysis of over 1 million men
22:02 Why the headline is inflated: three causes
22:27 Cause 1: The testing method changed (immunoassay to mass spec)
25:58 Cause 2: BMI cannot see visceral fat
29:37 The Nyante study: when you fix both problems, the decline vanishes
33:58 What this actually means for you
37:05 The broken testosterone system, summarized
38:24 Five takeaways from this episode
39:14 Next week: How testosterone actually works
39:39 About Signal and credits

What you'll learn in this episode:
 Why 25% of new TRT prescriptions are written without any pre-treatment lab work (JAMA, 2015)
What actually happens when researchers test 50+ "testosterone booster" supplements (spoiler: 12% are contaminated with undisclosed steroids)
Why a single low testosterone reading is not a diagnosis, and the Massachusetts Male Aging Study data that proves it
The real size of the population-level testosterone decline (much smaller than 1% per year)
Why BMI cannot see the visceral fat that is driving most of the genuine decline
The Nyante study that shows the decline essentially vanishes when you use an accurate test and measure waist circumference
Five practical takeaways you can apply before your next lab draw

This is Episode 1 of a four-part series built around our upcoming book, Signal. Over the next four weeks we cover what testosterone actually is, how to tell when it is genuinely low, what is really driving population-level changes, and what the evidence says you can do about it.
Next Steps
Check out our new book, Signal (coming soon)
For evidence-based resistance training programs: barbellmedicine.com/training-programs
For individualized training consultation: barbellmedicine.com/coaching
Explore our full library of articles on health and performance: barbellmedicine.com/resources
To consult with Drs. Baraki or Feigenbaum email us at [email protected]
To support us and get ad free listening, plus special product discounts, and exclusive content, go to supercast.barbellmedicine.com
Resources

Baillargeon, J., et al. (2015). Trends in Androgen Prescribing in the United States, 2001–2011. JAMA Intern Med, 175(8), 1413–1415. — 25% no preceding lab; post-prescription monitoring gap.

Rao, P.K., et al. (2017). Trends in Testosterone Replacement Therapy Use from 2003 to 2013 among Reproductive-Age Men in the United States. J Urol, 197(4), 1121–1126. — Prescription volume growth.

Selinger, S., & Thallapureddy, A. (2024). Cross-sectional analysis of national testosterone prescribing through prescription drug monitoring programs, 2018–2022. PLoS One, 19(8), e0309160. — Recent prescribing data, 3-4 million estimate.

Vesper, H.W., et al. (2015). Serum Total Testosterone Concentrations in the US Household Population from the NHANES 2011–2012 Study Population. Clin Chem, 61(12), 1495–1504. — Population testosterone levels, NHANES data.

Clemesha, C.G., et al. (2020). "Testosterone Boosting" Supplements Composition and Claims Are Not Supported by the Academic Literature. World J Men's Health, 38(1), 115–122. — 62% no published data, 10% decreased T.

Tucker, J., et al. (2018). Unapproved Pharmaceutical Ingredients Included in Dietary Supplements Associated With US FDA Warnings. JAMA Network Open, 1(6), e183337. — 12% adulterated with undisclosed steroids.

Trost, L.W., & Mulhall, J.P. (2016). Challenges in Testosterone Measurement, Data Interpretation, and Methodological Appraisal of Interventional Trials. J Sex Med, 13(7), 1029–1046. — Half of low results normalize on repeat.

Travison, T.G., et al. (2008). The Natural History of Symptomatic Androgen Deficiency in Men: Onset, Progression, and Spontaneous Remission. JCEM. MMAS data — 50%+ spontaneous normalization.

Travison, T.G., et al. (2007). A Population-Level Decline in Serum Testosterone Levels in American Men. JCEM, 92(1), 196–202. — Original MMAS secular decline, 15–20% lower across cohorts.
Santi, D., et al. (2025). Meta-analysis of secular trend in total testosterone levels, 1971–2024. 1,256 studies, N > 1,000,000. — 0.56%/year adjusted; LH parallel decline; mass spec subgroup no significant decline.
 Methods note on the ~0.56% per year figure cited in this episode: the Santi paper does not report a single percentage rate. The headline adjusted meta-regression coefficient (−0.6 nmol/L/year) is inflated by the random-effects weighting scheme and is not a biological rate. The 0.5–0.6% per year approximation comes from the pre-2000 stratified subgroup (Fig. 5, coefficient −0.1 nmol/L/year) divided by the dataset mean of 18.5 nmol/L. The post-2000 stratum runs larger (~1.1%), and the age-stratified coefficients in Table 5 cluster in the 0.4–0.9% range. The mass spectrometry subgroup (Table 3, Group 4) showed no significant trend (p = 0.845). The episode uses the conservative end of this range as the most defensible estimate of the real population-level rate after accounting for assay drift.

Nyante, S.J., Graubard, B.I., Li, Y., McQuillan, G.M., Platz, E.A., Rohrmann, S., Bradwin, G., & McGlynn, K.A. (2012). Trends in sex hormone concentrations in US males: 1988–1991 to 1999–2004. Int J Androl, 35(3), 456–466. doi: 10.1111/j.1365-2605.2011.01230.x. — Archived NHANES samples, same platform, waist circumference added; no significant decline in total or free testosterone.

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