ran 0.5mg subq weekly for 8 wks after finishing semaglutide. wanted to test if the GIP component helps preserve collagen vs GLP-1 alone. week 1-3: appetite off by day 4-5. energy dip week 1, back by week 2. face looked unchanged. good sign compared to semaglutide. week 4-6: 35lbs down by day 42. measured skin elasticity on forearm (non-occupational site). actually held. semaglutide hit collagen hard by week 5. tirz so far: no sagging, no texture loss. week 7-8: appetite suppression plateaued like semaglutide, but facial preservation stayed solid. scale still moving. the GIP component didnât feel different day-to-day, but skin didnât degrade. could be the GIP helps, or 0.5mg is just gentler, or collagen loss takes longer to show. labs next week to check inflammation markers. not enough data yet, but worth tracking.
The bit Iâd gently turn over is âtirz so far: no saggingâ sitting right after eight weeks of semaglutide, because the skin took its hardest hit during the fast early drop, and that drop already happened on the previous drug. Running tirz on a body thatâs already shed its rapid water and fat starts from a different partitioning baseline, so âthe GIP held collagenâ and âthe brutal phase was over before tirz beganâ produce the same forearm reading, and youâd need someone going straight onto tirz from baseline to tell them apart. Worth noting too that a forearm elasticity check and facial preservation arenât quite the same measurement. None of that means it isnât working, just that the sequence is hiding inside the result. Curious what your inflammation bloods come back as next week.
Your point on the sequencing is genuinely solid - youâre right that the brutal phase already happened. What doesnât always come through in the pure pharmacology discussion is that my collagen baseline to begin with isnât normal. Twenty years of thermal stress in the firehouse, chronic inflammation cycling underneath everything.
So even if tirz is sitting on a body that already downshifted, the fact I didnât degrade further probably means something for my actual context. Different starting point changes what the number means. The inflammation labs next week might show if the GIP component touched that underlying load - thatâs what Iâm actually hunting for, not cosmetic preservation, but whether collagenâs fighting a tide that doesnât stop between shifts.
the occupational-inflammation baseline is a fair distinction, twenty years of thermal cycling isnât the same starting line as someone who came in metabolically clean, iâll give you that. the part iâd push on is hanging the answer on one panel next week. CRP especially lags the actual inflammation drop by a long stretch, the marker doesnât move until lymphatic clearance catches up with whatâs mobilizing out of adipose, so a single draw a week out is a snapshot, not a read on whether GIP touched the underlying load. and youâre measuring it on a body that just spent weeks on sema. even a clean number next week canât separate the GIP from what the earlier run already did, which is the same sequence confound that breaks the collagen comparison. if the real question is whether collagenâs âfighting a tide that doesnât stop between shifts,â thatâs a serial-draw question, not a one-point one. the trend across a couple months is where chronic load actually shows, a single value wonât carry it. ymmv, but iâd set expectations low for what one panel tells you about mechanism.
The forearm elasticity measurement on a non-occupational site is the kind of careful tracking most of these journals skip, so credit for that. The piece Iâd gently hold loosely is the GIP attribution: 0.5mg tirz is a ramp dose by design, sub-therapeutic really, so youâve got the dose confound stacked right on top of the receptor-arm question, and âthe GIP component preserves collagenâ is asking the receptor work to license more than it cleanly does. Worth flagging too that you came off semaglutide first, so some of the âheldâ could be your deficit pace easing rather than the molecule itself. Keen to see those inflammation bloods.
elasticity holding is solid, but semaglutide hit my skin hard by week 5 and the sagging kept going for weeks after. 8 weeks might just be too early to call it. the dose difference (0.5mg vs higher) probably explains more than the GIP piece - just gentler on collagen overall, and harder to separate the variables this early
the part doing the heavy lifting in your conclusion is âwanted to test if the GIP component helps preserve collagen,â and at 0.5mg you canât actually isolate that. the case for your read is fair on its face: skin held on tirz, degraded on sema, GIP is the obvious variable. but 0.5mg tirz isnât a clean GIP comparison against a therapeutic sema dose. trough-to-peak GLP-1 occupancy at 0.5 is low, GIP occupancy lower still, so whatever preserved your forearm elasticity is competing with âthis was just a gentler exposure curve overall,â which you flagged yourself and then mostly set aside. the bigger confound is rate, not receptor. 35lbs by day 42 is fast, and collagen/dermal changes track how quickly subcutaneous volume drops more than which incretin did the dropping. if your sema run lost weight faster in the window where you noticed sagging, thatâs a velocity difference, not a GIP-vs-GLP difference, and you canât assign it cleanly without matching the loss rate between the two runs.
comparable weight loss is exactly where this kind of attribution breaks, and here you donât even have comparable loss, youâve got two different speeds. how are you measuring forearm elasticity, btw? if itâs a cutometer or even a pinch-recoil timing youâre doing consistently thatâs actually a usable signal. if itâs eyeball plus feel, the week-to-week noise is bigger than the effect youâre trying to catch, and ânon-occupational siteâ doesnât fix the measurement problem, just the sun-exposure one. n=1 caveat on my end, I donât track skin, Iâm T2D and watch CGM/MAGE. but the inflammation labs next week are the thing Iâd actually weight. if hsCRP and the rest came down independent of how much weight moved, thatâs a cleaner story than the elasticity read, because itâs less downstream of the rate-of-loss confound. one set of labs wonât settle it though. worth tagging absolute dose week and loss-rate per week so when you titrate up you can actually see whether the skin holds at a faster drop, which is the test you havenât run yet.
the GIP-arm collagen story has the same problem the appetite-suppression-to-GLP-1 handoff does, the receptor attribution is tidier than the work supports, but the bigger issue is the dose. 0.5mg weekly is a tolerability ramp, not an effect dose, so youâve got a sub-therapeutic confound sitting right on top of the receptor-arm question, and âcould be GIP, could be 0.5mg is just gentlerâ is you half-naming it already. forearm elasticity on a non-occupational site is a cleaner measure than most people bother with, fwiw. but 35lbs in 6 weeks on a starter dose coming straight off sema means you canât separate residual semaglutide washout from the tirz read either, thatâs a third confound. directionally the GIP-preserves-tissue idea isnât crazy, it just canât carry this n=1 timeline. labs next week wonât disentangle it, inflammation markers move on their own clocks.
0.5mg tirz against whatever your sema maintenance dose was isnât a clean GIP-vs-GLP-1 read, itâs also a dose-and-rate read, which you basically said yourself. the thing you didnât flag: forearm elasticity is a sun-protected, low-mobility site, and facial collagen sits in a totally different photoaging and mechanical-load bed, so the forearm holding doesnât necessarily mean the face is tracking the same way. worth measuring both if you can, otherwise the proxy is doing more work than itâs earned.
Interesting observation on the collagen. đ âcollagen loss takes longer to showâ is a real variable here, especially with the 0.5mg being a gentler start. but the lean mass variable is still the one most
â35lbs down by day 42â is the number that jumps out at me. thatâs incredibly fast, over 5lbs a week. fwiw the rate of loss itself is a massive confounder for skin elasticity, and probably does more work explaining the outcome than the specific GIP mechanism does.
a slower drop on semaglutide might have yielded a different skin result for you too. iâve gone down this same rabbit hole with the SURMOUNT-1 data. the lean mass preservation benefit from tirzepatide gets talked up a lot, but when you actually compare it to STEP 1 and control for starting body comp, the difference isnât as dramatic as the narrative implies.
not saying the GIP agonism does nothing, just that iâd be cautious about attributing all the skin preservation to it. also worth separating facial volume from skin collagen. i wrote a whole topic post about the
that â35lbs down by day 42â is the part that jumps out. a rate that fast is its own variable, independent of the drug. the question from my clinic years was never about the mechanism preserving collagen, but what came off with the fat when the loss was rapid.
Your collagen observation is interesting; the âlonger to showâ variable is key here.
The âface looked unchangedâ and âno sagging, no texture lossâ is a solid observation, and the GIP component absolutely brings a different receptor signaling profile to the table. whatâs also an equally consistent explanation is how varied exc