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From: Derek from Research Radar To: tjphuhs@gmail.com X-Mailgun-Tag: post X-Mailgun-Track-Clicks: false Message-Id: <20260428144324.3.65407b0cb2bfa7c3@mg-d1.substack.com> Date: Tue, 28 Apr 2026 14:43:24 +0000 Feedback-Id: post-195757749:cat-post:pub-3365367:substack Sender: Derek from Research Radar References: In-Reply-To: Reply-To: Derek from Research Radar List-Owner: List-Url: List-Archive: List-Id: List-Post: List-Unsubscribe: List-Unsubscribe-Post: List-Unsubscribe=One-Click X-Mailgun-Variables: {"category": "post", "email_generated_at": "1777387413182", "is_freemail": "true", "post_audience": "everyone", "post_id": "195757749", "post_type": "newsletter", "pub_community_enabled": "true", "publication_id": "3365367", "subdomain": "derekpruski", "user_id": "273622398"} --5626607ccecdb94d20814f00bf9c3c1898809ae8dee2df3d67f12b3bf9ca Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable View this post on the web at https://derekpruski.substack.com/p/do-glp-1s-k= ill-your-testosterone Got a great question in the inbox this week that deserves a full walkthroug= h. The framing was something like: =E2=80=9CMy RS is on a heavy weight-loss= compound, lost a ton of weight, and now reports profound lethargy and zero= libido. Is this anhedonia, or is testosterone actually crashing from the m= etabolic burn?=E2=80=9D The short answer is: it depends on how much weight loss, how fast, and from= what starting point. The same class of compounds can either fix low testos= terone or tank it, depending on where on the curve your RS is sitting. This= is one of the most misunderstood topics in the community right now, so let= =E2=80=99s walk through it from the ground up. Section 1: The basics =E2=80=94 how testosterone is actually made Before we touch any compound, you need to understand the system that produc= es testosterone. It=E2=80=99s a three-step relay called the HPG axis (hypot= halamic-pituitary-gonadal axis): Hypothalamus (a region of the brain) releases GnRH in pulses Pituitary gland responds by releasing LH and FSH into the bloodstream Testes respond to LH by producing testosterone in the Leydig cells Each step depends on the one before it. If the hypothalamus stops pulsing, = the pituitary stops releasing LH, and the testes stop making testosterone. = The signal flows downhill. Two more concepts that matter for everything that follows: SHBG (sex hormone binding globulin) is a protein that binds testosterone in= the blood. Bound testosterone is biologically inactive. Only free testoste= rone does anything in your tissues. Aromatase is an enzyme found heavily in body fat that converts testosterone= into estrogen. More body fat =3D more aromatase =3D more testosterone gett= ing siphoned into estrogen. Keep these in mind. They show up everywhere. Section 2: Why obese men have low testosterone in the first place Here=E2=80=99s the baseline most RS in this space are starting from. Obesit= y is a known driver of functional hypogonadism (low T not caused by a struc= tural problem with the testes or pituitary). Three reasons: Aromatase overload. Excess body fat means more aromatase, which converts mo= re testosterone into estrogen. The estrogen then signals back to the hypoth= alamus to slow GnRH release, suppressing the whole axis from the top. Insulin resistance. Impairs Leydig cell function and HPG signaling. Chronic inflammation. Adipose tissue releases inflammatory cytokines that f= urther suppress the axis. This is the population the GLP-1 trials are studying. So the starting line = for these studies is already low T, and the question becomes: does the comp= ound make it better or worse? Section 3: The data =E2=80=94 what GLP-1s actually do to testosterone This is where it gets interesting, because the answer flips depending on do= se, magnitude of weight loss, and how aggressive the deficit is. At moderate weight loss (~10-15%): testosterone goes UP Multiple studies in obese men show that GLP-1 therapy at standard doses rai= ses testosterone: 2025 EHR analysis (110 men, 18 months, semaglutide/tirzepatide/dulaglutide)= : Patients lost ~10% body weight. The proportion with normal total and free= testosterone went from 53% to 77%. Average total T rose by 18%. 2024 Slovenian RCT (semaglutide vs TRT in obese diabetic men with hypogonad= ism): 6.5% weight loss in the semaglutide group produced a 1.6 nmol/L incre= ase in total testosterone. Semaglutide was actually superior to TRT for bod= y composition and matched TRT on total T improvement. 2025 Italian pilot study (tirzepatide vs TRT vs lifestyle, 83 obese hypogon= adal men, 8 weeks): Tirzepatide produced larger increases in free and total= testosterone than transdermal TRT, plus better body composition and erecti= le function. The lead author called it a candidate for =E2=80=9Cfirst-line = management=E2=80=9D of metabolic hypogonadism. The mechanism is exactly what you=E2=80=99d predict from Section 2: less fa= t =3D less aromatase =3D less testosterone-to-estrogen conversion =3D the H= PG axis comes back online. Better insulin sensitivity and lower inflammatio= n amplify the effect. So at moderate doses producing moderate loss in obese men, GLP-1s and dual-= agonists fix low testosterone. They don=E2=80=99t kill it. At aggressive weight loss (20%+): the curve flips This is where most of the community confusion comes from. The benefit-to-co= st ratio inverts at the high end. The triple-agonist class (Peptide-R) is producing weight loss in a differen= t league than its predecessors: Semaglutide: ~15% loss at 68 weeks (STEP 1) Tirzepatide: ~21% loss at 72 weeks (SURMOUNT-1) Peptide-R (triple-agonist): ~24% at 48 weeks (phase 2), and 28.7% at 68 wee= ks in the recent phase 3 TRIUMPH-4 readout. Placebo-adjusted: 26.6%. Once weight loss gets that aggressive, you=E2=80=99re no longer just droppi= ng fat =E2=80=94 you=E2=80=99re forcing the body into sustained caloric def= icit territory that the HPG axis interprets as famine. And the famine respo= nse is well-documented: US Army Ranger course (8 weeks, ~2,200 kcal/day, heavy exercise): total tes= tosterone dropped 70-80%. SHBG rose 46-60%. Recovery took ~6 weeks after th= e course ended. US Marines in SERE training (7 days, ~300 kcal/day, ~85% deficit): mean tes= tosterone fell from 17.5 nmol/L to 9.8 nmol/L. The Marines who landed in th= e low-T group lost significantly more lean body mass than those who maintai= ned T. 3-week experimental caloric restriction in healthy men: testosterone droppe= d 2.8 nmol/L, fully reversible by refeeding. 2019 case series in Clinical Endocrinology: 23 men with reversible hypogona= dism driven purely by energy deficit. Median total testosterone: 3.0 nmol/L= (~86 ng/dL). 91% showed the central (low-LH) suppression pattern. The mechanism: severe energy deficit raises cortisol and reduces hypothalam= ic GnRH pulse frequency. Less GnRH means less LH, which means less testoste= rone. The body is choosing survival over reproduction. Now overlay this on a triple-agonist producing 25%+ body weight loss. If yo= ur RS is already at a relatively healthy body fat percentage and pushing fu= rther, or running aggressive doses with deep appetite suppression, they=E2= =80=99re sitting in famine-physiology territory. The HPG axis crashes accor= dingly. The U-curve This is the simplest way to think about it: Starting obese, moderate loss =E2=86=92 testosterone improves (fat-loss ben= efit dominates) Starting obese, aggressive loss past necessary =E2=86=92 testosterone start= s to suppress (deficit penalty starts to bite) Starting lean, any meaningful loss =E2=86=92 testosterone suppresses (no ar= omatase benefit to harvest, just deficit) The original question =E2=80=94 RS reporting profound lethargy and libido l= oss on a heavy compound =E2=80=94 almost always means they=E2=80=99ve cross= ed the inflection point. Section 4: The total T vs. free T trap Worth flagging because it trips up a lot of RS pulling labs. Energy deficit consistently raises SHBG. The Ranger and Marine studies show= 20-60% increases. So even if total testosterone looks =E2=80=9Cfine=E2=80= =9D on paper, free testosterone =E2=80=94 the active fraction =E2=80=94 can= be dramatically lower because more of the total is bound up. If your RS pulls labs and only checks total T, the picture looks better tha= n it is. Always pull total T, free T, and SHBG together. Otherwise you=E2= =80=99re guessing. Section 5: Why it=E2=80=99s not just hormones =E2=80=94 the libido layer One more piece, because this is where RS often misdiagnose what=E2=80=99s h= appening to them. GLP-1 receptors are expressed in the VTA and project into the nucleus accum= bens =E2=80=94 the brain=E2=80=99s dopamine reward circuit. Chronic GLP-1 a= ctivation blunts phasic dopamine bursts across all rewards, not just food. = Sex, music, social connection, achievement =E2=80=94 all run through the sa= me dopaminergic pathways. So even if testosterone were perfectly normal, an RS on a GLP-1 class compo= und would still likely report flattened libido and motivation. In practice,= low T and dopamine blunting hit at the same time and look identical from t= he outside. This is why just stacking exogenous testosterone often doesn=E2= =80=99t fully resolve the symptoms in this population =E2=80=94 you=E2=80= =99re treating one of two overlapping problems. Section 6: Compounding factors that make it worse A few things that consistently make the testosterone picture worse than the= deficit alone would predict: Micronutrient depletion. Severe appetite suppression often means undereatin= g zinc, magnesium, vitamin D, and protein =E2=80=94 all required for testos= terone synthesis. Zinc is specifically required for SHBG conformation and i= s a direct cofactor in steroidogenesis. Low zinc + high SHBG =3D double hit= on free T. Cortisol elevation. The HPA and HPG axes are reciprocally inhibitory. Susta= ined energy deficit elevates cortisol, which independently suppresses GnRH = release. Cortisol up, testosterone down. Sleep disruption. GI side effects, dose titration, and rapid body compositi= on change all hit sleep architecture. Most testosterone production happens = during REM. Bad sleep compounds the suppression. Section 7: Protocol logic to consider (research framing) Where the right approach lands depends entirely on which side of the U-curv= e your RS is on. Important caveat: I=E2=80=99m not a clinician. None of this is medical advi= ce. Anyone running these compounds in any human capacity should be working = with a clinician monitoring full labs (total T, free T, LH, FSH, SHBG, estr= adiol, prolactin, fasting insulin, cortisol, full thyroid panel). If your RS is obese and on a moderate dose The data suggests testosterone will likely improve as weight comes off. The= intervention is mostly hands-off: stay the course, support with adequate p= rotein and micronutrients, monitor labs. Don=E2=80=99t reflexively add test= osterone =E2=80=94 for many men in this category, the GLP-1 itself is doing= the testosterone work better than TRT would. If your RS is on a heavy compound (high-dose tirzepatide, Peptide-R, or any= one past the inflection point) First lever: address the deficit itself. Most RS dosing aggressive compound= s are running deeper deficits than necessary because appetite suppression i= s so strong they lose track of intake. The Ranger and Marine data shows ful= l reversibility within ~6 weeks of energy restoration. A structured 1.6-2.2= g/kg protein floor and adequate total kcal often partially restores HPG ax= is function on its own. Second-line considerations from research literature: Peptide-K (kisspeptin-10). Top-down stimulation at the hypothalamus, prompt= ing endogenous GnRH pulsatility. Logical match for central suppression beca= use it acts upstream of the bottleneck. Gonadorelin. GnRH analog =E2=80=94 pituitary-level support. Some community = protocols stack this with kisspeptin to hit two levels of the axis. Enclomiphene. SERM (small molecule, not a peptide =E2=80=94 flagging that e= xplicitly) that blocks estrogen negative feedback at the pituitary, which i= ncreases endogenous LH/FSH output. Micronutrient floor: zinc, magnesium, vitamin D, adequate dietary fat. Foun= dational, not optional. The argument against stacking TRT or hCG concurrently with an active heavy = compound is that you=E2=80=99re masking a signal. The HPG suppression is in= formation about how aggressive the deficit is. Adding exogenous testosteron= e doesn=E2=80=99t fix the cortisol elevation, the micronutrient depletion, = or the reward circuit blunting =E2=80=94 it just smooths over the lab value= s while the upstream pressure stays intact. If your RS is coming off Standard washout logic applies. The 2019 case series showed gonadal recover= y within ~6 weeks of energy restoration. That matches our broader washout p= hilosophy: full 4-6+ weeks off before considering bridge protocols, eating = at maintenance, sleep dialed in, training volume normalized. If labs at the 6-week mark still show suppression, then the kisspeptin / go= nadorelin / enclomiphene logic comes in for a structured restart. What I=E2=80=99d avoid: bridging directly from one heavy compound into anot= her targeting the same metabolic receptors, or stacking exogenous testoster= one without a clear plan to either commit to lifelong supplementation or ru= n a proper restart. Section 8: The bottom line Do GLP-1s kill your testosterone? Not in the way most people think. At moderate doses producing moderate weight loss in obese men, GLP-1s and d= ual-agonists actually raise testosterone =E2=80=94 sometimes outperforming = TRT itself for body composition and matching it on T levels. The fat-loss b= enefit (less aromatase, better insulin sensitivity, less inflammation) over= whelms the deficit penalty. But push the same class harder =E2=80=94 high doses, the new triple-agonist= s, aggressive sustained deficits, lean starting points =E2=80=94 and the cu= rve flips. Once you cross into famine physiology, the HPG axis suppresses c= entrally, SHBG rises, free T drops, and the dopamine reward circuit blunts = on top. That=E2=80=99s the picture the original question described. Action items for any RS feeling the crash: Pull a full panel. Total T, free T, LH, FSH, SHBG, estradiol, prolactin, co= rtisol. Without this you=E2=80=99re guessing. Audit intake honestly. Most RS on heavy compounds are eating less than they= think. The appetite suppression is doing more than fat loss =E2=80=94 it= =E2=80=99s driving the HPG suppression. Locate yourself on the U-curve. Obese with 10% loss? Probably trending up. = Already lean and pushing harder? You=E2=80=99ve crossed the inflection. Don=E2=80=99t reflexively stack TRT. It masks the upstream signal and leave= s the metabolic stress in place. Decide the path. Continue and support, or wash out and restart. Drifting wi= th no plan is what creates problems. Got data, lab work, or protocol experience to share on this? Drop it in the= comments. The formal literature on triple-agonists and testosterone is sti= ll thin because the compound is new =E2=80=94 what=E2=80=99s emerging is a = pattern, and community-level data points make the picture clearer. For research subjects only. Nothing in this post is medical advice or a rec= ommendation for human use. 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Got a great question in the inbox this week th= at deserves a full walkthrough.
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Do GLP-= 1s Kill Your Testosterone?

Derek
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READ IN APP3D""
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Got a great = question in the inbox this week that deserves a full walkthrough. The frami= ng was something like: “My RS is on a heavy weight-loss co= mpound, lost a ton of weight, and now reports profound lethargy and zero li= bido. Is this anhedonia, or is testosterone actually crashing from the meta= bolic burn?”

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The short answer is: it depends on how much weigh= t loss, how fast, and from what starting point. The same cla= ss of compounds can either fix low testosterone or tank it, depending on wh= ere on the curve your RS is sitting. This is one of the most misunderstood = topics in the community right now, so let’s walk through it from the = ground up.

Section 1: The basics — how testost= erone is actually made

Before we touch any compound,= you need to understand the system that produces testosterone. It’s a= three-step relay called the HPG axis (hypoth= alamic-pituitary-gonadal axis):

  1. Hypothalamus (a region= of the brain) releases GnRH in pulses

  2. Testes respond to LH by producing testosterone in the Leydig cells

Each step depends on the one before it. If t= he hypothalamus stops pulsing, the pituitary stops releasing LH, and the te= stes stop making testosterone. The signal flows downhill.

T= wo more concepts that matter for everything that follows:

  • SHBG (sex hormone binding globulin) is a protein th= at binds testosterone in the blood. Bound testosterone is biologically inac= tive. Only free testosterone does anything in= your tissues.

  • Aromatase is an enzyme found heavily in body fa= t that converts testosterone into estrogen. More body fat =3D more aromatas= e =3D more testosterone getting siphoned into estrogen.

    • Keep these in mind. They show up everywhere.

    = Section 2: Why obese men have low testosterone in the first place

    Here’s the baseline most RS in this space are starting = from. Obesity is a known driver of functional hypogonadism (low T not caused by a structural problem with the testes or = pituitary). Three reasons:

      Aromatase overload. Excess = body fat means more aromatase, which converts more testosterone into estrog= en. The estrogen then signals back to the hypothalamus to slow GnRH release= , suppressing the whole axis from the top.

    1. Insulin resistance. Impairs Leydig cell functi= on and HPG signaling.

    2. Chronic= inflammation. Adipose tissue releases inflammatory cytokine= s that further suppress the axis.

    Th= is is the population the GLP-1 trials are studying. So the starting line fo= r these studies is already low T, and the question be= comes: does the compound make it better or worse?

    Se= ction 3: The data — what GLP-1s actually do to testosterone

    This is where it gets interesting, because the answer flips dependi= ng on dose, magnitude of weight loss, and how aggressive the deficit is.

    At moderate weight loss (~10-15%): testosterone goes UP

    Multiple studies in obese men show that GLP-1 therapy a= t standard doses raises testosterone:

    • 2025 EHR analysis (110 men, 18 months, semaglutide/tirzep= atide/dulaglutide): Patients lost ~10% body weight. The prop= ortion with normal total and free testosterone went from 53%= to 77%. Average total T rose by 18%.

    • 2024 Slovenian RCT (sema= glutide vs TRT in obese diabetic men with hypogonadism): 6.5= % weight loss in the semaglutide group produced a 1.6 nmol/L increase in to= tal testosterone. Semaglutide was actually superior to TRT for body composi= tion and matched TRT on total T improvement.

    • 2025 Italian pilot study (tirzep= atide vs TRT vs lifestyle, 83 obese hypogonadal men, 8 weeks): Tirzepatide produced larger increases in free and total t= estosterone than transdermal TRT, plus better body compositi= on and erectile function. The lead author called it a candidate for “= first-line management” of metabolic hypogonadism.

      • The mechanism is exactly what you’d predict from Sectio= n 2: less fat =3D less aromatase =3D less testosterone-to-estrogen conversi= on =3D the HPG axis comes back online. Better insulin sensitivity and lower= inflammation amplify the effect.

      So at moderate dose= s producing moderate loss in obese men, GLP-1s and dual-agon= ists fix low testosterone. They don’t kill it.<= /p>

      At aggressive weight loss (20%+): the curve flips

      This is where most of the community confusion comes from. The ben= efit-to-cost ratio inverts at the high end.

      The triple-agon= ist class (Peptide-R) is producing weight loss in a different league than i= ts predecessors:

      • Semaglutide: ~15%= loss at 68 weeks (STEP 1)

      • Tirzepatide: ~21% loss at 72 weeks = (SURMOUNT-1)

      • Peptide-R (triple-agonist): ~24% at 48 weeks (pha= se 2), and 28.7% at 68 weeks in the recent ph= ase 3 TRIUMPH-4 readout. Placebo-adjusted: 26.6%.

      Once weight loss gets that aggressive, you’re no longer= just dropping fat — you’re forcing the body into sustained cal= oric deficit territory that the HPG axis interprets as famin= e. And the famine response is well-documented:

    • US Army Ranger course (8 weeks, ~2,200 k= cal/day, heavy exercise): total testosterone dropped 70-80%<= /strong>. SHBG rose 46-60%. Recovery took ~6 weeks after the course e= nded.

    • US Marines in SERE training (7 days, ~300 kcal/day, ~85%= deficit): mean testosterone fell from 17.5 nmol/L to 9.8 nmol/L. The Marin= es who landed in the low-T group lost significantly more lean body mass tha= n those who maintained T.

    • 3-week experimental caloric restriction in healthy men: testosterone dropped 2.8 nmol/L, fully reversible by re= feeding.

    • <= strong>2019 case series in Clinical Endocrinology: 23 men with reversible hypogonadism drive= n purely by energy deficit. Median total testosterone: 3.0 nmol/L (~86 ng/d= L). 91% showed the central (low-LH) suppression pattern.

      • The mechanism: severe energy deficit raises cortisol and red= uces hypothalamic GnRH pulse frequency. Less GnRH means less LH, which mean= s less testosterone. The body is choosing survival over reproduction.

      Now overlay this on a triple-agonist producing 25%+ body= weight loss. If your RS is already at a relatively healthy = body fat percentage and pushing further, or running aggressive doses with d= eep appetite suppression, they’re sitting in famine-physiology territ= ory. The HPG axis crashes accordingly.

      The U-curve=

      This is the simplest way to think about it:

      • Starting obese, moderate loss → testosterone improves (fat-loss benefit dominates)

      • Starting obese, aggressive loss pa= st necessary → testosterone starts to suppress (defici= t penalty starts to bite)

      • Starting lean, any meaningful loss → testoste= rone suppresses (no aromatase benefit to harvest, just defic= it)

      The original question — RS repor= ting profound lethargy and libido loss on a heavy compound — almost a= lways means they’ve crossed the inflection point.

      Sec= tion 4: The total T vs. free T trap

      Worth flagging because= it trips up a lot of RS pulling labs.

      Energy deficit= consistently raises SHBG. The Ranger and Mar= ine studies show 20-60% increases. So even if total testosterone looks R= 20;fine” on paper, free testosterone &#= 8212; the active fraction — can be dramatically lower because more of= the total is bound up.

      If your RS pulls labs and on= ly checks total T, the picture looks better than it is. Always pull total T= , free T, and SHBG together. Otherwise you’re guessing.

      Section 5: Why it’s not just hormones — the libido layer

      One more piece, because this is where RS often misdiagnose wh= at’s happening to them.

      GLP-1 receptors are exp= ressed in the VTA and project into the nucleus accumbens — the brain’s dopamin= e reward circuit. Chronic GLP-1 activation blunts phasic dopamine bursts ac= ross all rewards, not just food. Sex, music, social connection, achievement= — all run through the same dopaminergic pathways.

      So even if testosterone were perfectly normal, an RS on a GLP-1 = class compound would still likely report flattened libido and motivation. I= n practice, low T and dopamine blunting hit at the same time and look ident= ical from the outside. This is why just stacking exogenous t= estosterone often doesn’t fully resolve the symptoms i= n this population — you’re treating one of two overlapping prob= lems.

      Section 6: Compounding factors that make it wo= rse

      A few things that consistently make the testosterone p= icture worse than the deficit alone would predict:

      = Micronutrient depletion. Severe appetite suppression often m= eans undereating zinc, magnesium, vitamin D, and protein — all requir= ed for testosterone synthesis. Zinc is specifically required for SHBG confo= rmation and is a direct cofactor in steroidogenesis. Low zinc + high SHBG = =3D double hit on free T.

      Cortisol elevation= =2E The HPA and HPG axes= are reciprocally inhibitory. Sustaine= d energy deficit elevates cortisol, which independently suppresses GnRH rel= ease. Cortisol up, testosterone down.

      Sleep = disruption. GI side effects, dose titration, and rapid body = composition change all hit sleep architecture. Most testosterone production= happens during REM. Bad sleep compounds the suppression.

      Section 7: Protocol logic to consider (research framing)

      Where the right approach lands depends entirely on which side of the U= -curve your RS is on.

      Important caveat: I’m not a clinician. None of this is medical advice. Anyone runni= ng these compounds in any human capacity should be working with a clinician= monitoring full labs (total T, free T, LH, FSH, SHBG, estradiol, prolactin= , fasting insulin, cortisol, full thyroid panel).

      = If your RS is obese and on a moderate dose

      The data = suggests testosterone will likely improve as = weight comes off. The intervention is mostly hands-off: stay the course, su= pport with adequate protein and micronutrients, monitor labs. Don’t r= eflexively add testosterone — for many men in this category, the GLP-= 1 itself is doing the testosterone work better than TRT would.

      If your RS is on a heavy compound (high-dose tirzepatide, Pept= ide-R, or anyone past the inflection point)

      First = lever: address the deficit itself. Most RS dosing aggressive= compounds are running deeper deficits than necessary because appetite supp= ression is so strong they lose track of intake. The Ranger and Marine data = shows full reversibility within ~6 weeks of energy restoration. A structure= d 1.6-2.2 g/kg protein floor and adequate total kcal often partially restor= es HPG axis function on its own.

      Second-line= considerations from research literature:

      • Peptide-K (kisspeptin-10). Top-down stimulation at the hyp= othalamus, prompting endogenous GnRH pulsatility. Logical match for central= suppression because it acts upstream of the bottleneck.

        • Gonadorelin. GnRH analog — pituitary-level support. Some community protoco= ls stack this with kisspeptin to hit two levels of the axis.

      • Enclomiphene. SERM (small molecule, not a peptide — flagging that expl= icitly) that blocks estrogen negative feedback at the pituitary, which incr= eases endogenous LH/FSH output.

      • Micronutrient floor: zinc, mag= nesium, vitamin D, adequate dietary fat. Foundational, not optional.=

      The argument against stacking TRT or hCG concurrently with an active heavy compound is = that you’re masking a signal. The HPG suppression is information abou= t how aggressive the deficit is. Adding exogenous testosterone doesn’= t fix the cortisol elevation, the micronutrient depletion, or the reward ci= rcuit blunting — it just smooths over the lab values while the upstre= am pressure stays intact.

      If your RS is coming of= f

      Standard washout logic applies. The 2019 case series sho= wed gonadal recovery within ~6 weeks of energy restoration. That matches ou= r broader washout philosophy: full 4-6+ weeks off before considering bridge= protocols, eating at maintenance, sleep dialed in, training volume normali= zed.

      If labs at the 6-week mark still<= /strong> show suppression, then the kisspeptin = / gonadorelin / enclomiphene logic comes in for a structured restart.

      What I’d avoid: bridging directly from one heavy co= mpound into another targeting the same metabolic receptors, or stacking exo= genous testosterone without a clear plan to either commit to lifelong suppl= ementation or run a proper restart.

      Section 8: The bottom l= ine

      Do GLP-1s kill your testosterone? Not in the way most people think.

      At modera= te doses producing moderate weight loss in obese men, GLP-1s and dual-agoni= sts actually raise testosterone — sometimes out= performing TRT itself for body composition and matching it on T levels. The= fat-loss benefit (less aromatase, better insulin sensitivity, less inflamm= ation) overwhelms the deficit penalty.

      But push the = same class harder — high doses, the new triple-agonists, aggressive s= ustained deficits, lean starting points — and the curve flips. Once y= ou cross into famine physiology, the HPG axis suppresses centrally, SHBG ri= ses, free T drops, and the dopamine reward circuit blunts on top. That̵= 7;s the picture the original question described.

      Action ite= ms for any RS feeling the crash:

      1. Pull a full panel. Total T, = free T, LH, FSH, SHBG, estradiol, prolactin, cortisol. Without this youR= 17;re guessing.

      2. Audit intake = honestly. Most RS on heavy compounds are eating less than th= ey think. The appetite suppression is doing more than fat loss — it&#= 8217;s driving the HPG suppression.

      3. <= strong>Locate yourself on the U-curve. Obese with 10% loss? = Probably trending up. Already lean and pushing harder? You’ve crossed= the inflection.

      4. Don’t = reflexively stack TRT. It masks the upstream signal and leav= es the metabolic stress in place.

      5. Decide the path. Continue and support, or wash out and = restart. Drifting with no plan is what creates problems.

        6. =

        Got data, lab work, or protocol experience to share on= this? Drop it in the comments. The formal literature on tri= ple-agonists and testosterone is still thin because the compound is new = 212; what’s emerging is a pattern, and community-level data points ma= ke the picture clearer.

        For research subjects only. = Nothing in this post is medical advice or a recommendation for human use.

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You're currently a free = subscriber to Research Radar. For the full experience, upgrade your subscription.<= /span>

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© 2026 Derek Pruski
548 Market Street PMB 72296, San Francisco, CA 94104
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