CommunityStacking & Switching

Tirz to Reta exploration is NOT going well.

42 replies21 peopleApr 6, 2026☆ Follow
Summary

what happens when switching from tirzepatide to retatrutide and how to handle hunger and transition issues

The original poster tested a switch from tirz to reta after stockpiling both and experienced strong hunger on low reta doses during the changeover. Several users reported similar early hunger with reta, advised slower overlaps or stacking instead of abrupt stops, and noted that tirz tends to suppress appetite more while reta may boost metabolism. Some returned to tirz after trying reta, while others found low-dose combinations workable once adjusted.

What this discussion establishesWhere people disagree

whether to stack both peptides during transition or switch completely before starting the new one, and how much weight to give warnings about receptor overstimulation

Still open

long-term preference between the two compounds once past the initial adjustment phase

Nothing here is advice.

42 replies · 21 people
SteadyQuill55archiveopening postApr 6

I've been using tirz since late June of last year and added a small amount of survo on top starting around November or December mainly to ease fatigue, though I don't plan to keep the survo once I reach maintenance. I've dropped nearly all the extra weight and am nearing the finish line. I have a large supply of high-dose tirz stored away and have mostly stopped worrying about running out. I began setting aside some reta without any plan to use it soon because I prefer waiting for more real-world data on newer meds, but I thought I should test it for a few months now so I know how it sits with me before committing later. My plan is to taper back down afterward and return to tirz for the time being.

AmberAlder58archiveApr 6

If the only reason you're moving to reta is fear of missing out, I'd stay with tirz since it was already doing what you wanted. Is there another motive for the change, like wanting the glucagon action? I'd avoid pushing the reta dose higher right now because any sides that show up could land hard.

CopperBeacon48archiveApr 6

The body has to get used to reta and appetite control isn't as quick or strong as with tirz. It takes time, so you need a steady meal plan that fits you, plenty of water each day, and dosing every day because results aren't instant is a mistake. These things don't happen overnight.

SharpCinder28archiveApr 6

Some people keep both going at once, especially while moving from one to the other. I stay mostly on tirz but add reta now and then just to see. From what I've read the biggest error during a switch is dropping tirz right away or moving too quickly without enough overlap weeks. Stopping tirz first before starting reta looks safer on paper since there are no stacking studies, and some tirz stays in the system for weeks anyway.

SteadyQuill55archiveApr 6
↳ replying to @AmberAlder58

If the reta ends up working well or even better once I reach a good dose, I'll keep what I have and still pick up more now and then to store. I'm concerned grey sources might disappear or get much harder to find in the future. If it never suits me and tirz stays clearly better after a fair trial, then I'll stop buying extra because it's not for me. Either way I still intend to go back to tirz for now once the test period ends.

SteadyQuill55archiveApr 6
↳ replying to @CopperBeacon48

I didn't expect results right away. I just started doubting the low dose because I wasn't beginning from zero after already being on a moderate amount of the other meds. I already follow a diet that works for me and has for a while. Suddenly that same low-carb high-protein approach with lots of water isn't cutting it and the hunger is intense.

SteadyQuill55archiveApr 6
↳ replying to @SharpCinder28

I was planning to overlap them, but then a video from a guy in a baseball cap and beard made me worry about possible pancreas damage from doing that. I figured if there was even a small chance he was right it wasn't worth the risk, so I switched and tried to titrate faster without the overlap. That choice might be backfiring.

KeenSignal54archiveApr 6
↳ replying to @SteadyQuill55 (opening post)

Right now you're not only testing reta, you're also dealing with the loss of tirz at the same time. That overlap makes it tough to know what's really causing the issues. I'd spend less time chasing the perfect reta dose early on and more time getting through a clean switch first. Otherwise it's easy to blame reta for effects that are really just the gap from stopping tirz, especially with that pre-period week involved. Low reta doses leave me very hungry too, at least at the start.

SteadyQuill55archiveApr 6
↳ replying to @KeenSignal54

I've been checking the numbers too. With my last 8.8 mg dose on the 16th and steady state reached, the amount left now should be around 0.66 mg. That's near enough to zero that I can say this is how the current reta dose feels. I'm glad I never dismissed people who complained about strong hunger on low reta. It sounded backwards at the time, but now that I'm in it I see how rough it is.

SharpCinder28archiveApr 6
↳ replying to @SteadyQuill55

This is why more places should offer lira. Not many do, though it comes as a generic pen from overseas. The shorter half-life lets you add a GLP boost without as much worry about later problems.

IronThistle42archiveApr 6
↳ replying to @SteadyQuill55

You could shift your view a bit and see that even if grey sources fade, demand for reta will stay high and market forces will keep working. Those occasional reta kits you buy and never use could end up worth a lot more later. That way the hoarding habit stays fun without having to quit it entirely.

NorthKettle44archiveApr 6
↳ replying to @SteadyQuill55

Did that doctor with the hat back up the pancreas claim with anything? Has anyone else seen data on this? It's new to me.

LevelThistle44archiveApr 6
↳ replying to @SteadyQuill55 (opening post)

Everyone has their own take, so here are my observations. What dose of tirz were you on? I began compounded tirz at 2.5 mg twice a week until early January when I moved to reta. My first week on reta totaled 7 mg across six doses. I've had six tirz doses since starting the bridge for 14 mg total, and 34 reta doses adding up to 143 mg. That works out to about 11.6 mg per week on average, with many small doses early to build levels without overshooting into sides. I switched for the glucagon signaling to raise metabolic rate and help spare lean mass better than tirz alone. That signaling depends on dose, so titrating reta by appetite or food noise isn't the right approach. I went by side tolerance aiming for 8 mg or more weekly for real glucagon effect. I use tirz as needed mainly for food noise rather than hunger, since noise has been my bigger long-term issue. I'll still add a bit if I expect trouble ahead.

SteadyQuill55archiveApr 6
↳ replying to @SharpCinder28

The goal was to check whether I needed to keep buying these, not end up buying even more to make the ones I might not need work better. I'll go order more survo just in case I run out.

SharpCinder28archiveApr 6
↳ replying to @NorthKettle44

It's mostly the lack of any studies. There are none on stacking any of these. So my doctor treats the idea of combining the two as risky.

SteadyQuill55archiveApr 6
↳ replying to @IronThistle42

You know, that might actually be the better way to look at it.

SteadyQuill55archiveApr 6
↳ replying to @SharpCinder28

It was that one YouTube video, and I can't stress enough that I wouldn't normally listen to that guy for even a second. But someone shared the video one night when I was already tired and unsure, so I read the transcript.

WarmAlder92archiveApr 6
↳ replying to @SteadyQuill55 (opening post)

I did a quick switch from about 7.5 mg tirz to around 6 mg reta over roughly five weeks. I split the early shots like you did, then moved to weekly spacing to get the peak glucagon effect. The main warning is that it caused odd stomach issues even with lots of water, electrolytes, and fiber. Things alternated between constipation and loose stools, plus a full stop for three days that worried me enough to use laxatives. Gastroparesis is serious. Later everything settled except for some skin sensitivity that faded at steady dose. Eventually aches returned and I went back to the earlier tirz plus survo combo. I might try something else with higher tirz instead. Good luck, but watch the stomach effects closely.

NorthKettle44archiveApr 6
↳ replying to @SteadyQuill55

I looked at the video out of curiosity. The whole argument rests on stacking causing receptor overstimulation and then retreat, plus the claim that glucagon signaling works against the other two. Yet reta itself hits all three receptors, so why wouldn't it contradict itself? The logic seems to assume max doses of both at once. If you're using lower or moderate amounts of each, say half or less of trial maximums, it shouldn't overstimulate any more than a full dose of either alone.

KeenSignal54archiveApr 6
↳ replying to @SteadyQuill55

It only feels backwards until you're the one living it. I wouldn't assume it's not working yet. It may just be the transition window where appetite hasn't settled, so I wouldn't push the dose quickly. Waiting another week or two lets the body adjust, and when you do go up it tends to go smoother with fewer sides.

SteadyQuill55archiveApr 6
↳ replying to @WarmAlder92

Thanks for sharing that. I'll keep it in mind. Your switch numbers are close to what I'm looking at, so the details help. I've never had digestive trouble from any of these before, but gastroparesis still sounds frightening.

SteadyTimber49archiveApr 6

I'm having the exact opposite experience. I've been on reta, lost a lot of weight, and thought I'd try tirz for maintenance since it's cheaper and might ease some skin and sleep issues. I was at 5 mg reta and added 5 mg tirz two days ago, and now I'm extremely hungry. Maybe whichever one you start with just works best for you.

LevelThistle44archiveApr 6
↳ replying to @SteadyTimber49

My long-term maintenance plan leans toward tirz to reduce the glucagon signaling and give everything a break after the big weight loss. I still have time to change my mind. Cost isn't a factor since the difference is tiny and I have plenty of both on hand.

SharpCinder28archiveApr 6
↳ replying to @SteadyTimber49

Another idea is that it's similar to switching antidepressants. The fact that the last one wasn't ideal for your current state doesn't mean the next one will be better. Reta has felt different to me at different times, and so has tirz. We're always changing biologically.

QuietAnchor73archiveApr 6
↳ replying to @SteadyQuill55

That guy has no real standing. His license as a chiropractor was pulled years ago by the state board, and he tends to reference studies that don't exist.

BlueSignal49archiveApr 6
↳ replying to @SteadyQuill55

I watched that same video and turned it off the moment he called tirz trash and claimed he wasn't selling anything. I don't understand why anyone listens to someone whose knowledge seems to come from AI like the rest of us.

BlueSignal49archiveApr 6
↳ replying to @QuietAnchor73

I'm saving that link to drop in every thread that brings him up.

ClearWillow59archiveApr 6
↳ replying to @SteadyQuill55 (opening post)

I'd stay on tirz and add reta gradually over time. Drop tirz by 1 mg and add 1 mg reta, pinning them separately every few days. The body needs time to adapt to new things.

WrySparrow92archiveApr 6

I wasn't sure if I should share this here or keep it to myself. Right now I'm using 4.5 of reta along with 2.5 tirz and 1 sema. Four years back I began with sema. I reached 2.4 before introducing tirz into the mix. For me nothing else reduces the constant thoughts about eating like sema does. Last year I paused all of it for two months because of some health concerns and procedures involving BC. During that time I felt extremely hungry all the time and put on about seven or eight pounds. That experience really showed me I need to stay on a version of these medications as long as possible. Once I restarted the GLPs I began solely with reta going gradually. The urge to eat remained overwhelming so I incorporated sema again. I noticed my hands were still in pain unlike when I had tirz in my regimen which is why I brought back the 2.5 dose. Things feel balanced for me at the moment. I also use a pen with GHK-Cu and KPV.

SharpHarbour71archiveApr 6
↳ replying to @ClearWillow59

That's exactly how I moved from reta to tirz with no problems. A low and slow back-and-forth between the two is what worked.

SteadyQuill55archiveApr 6
↳ replying to @SharpHarbour71

You know what, I'm going to stop overthinking and follow that same gradual method both the rest of the way to reta and then back again later. Once I write out that I let a discredited online video get in my head and now feel awful, it seems silly. The slow shuffle approach makes more sense.

WarmAlder92archiveApr 6
↳ replying to @SteadyQuill55

The only time I had real stomach trouble was during the move to reta. I'm glad I was dosing every three days instead of daily so I could catch the issue before increasing further.

PlainAlder11archiveApr 6

I don't have advice since I've been on reta alone for three months. Why the unusual dose steps like 2.2, 4.4, and 6.6? Just wondering.

SteadyQuill55archiveApr 7
↳ replying to @PlainAlder11

I kept using the same concentration I started with on the compounded version, which is 22 mg per ml. That turns 10 units into 2.2 mg, 20 units into 4.4 mg, and so on. I could have changed the strength and the doses but never got around to it. Keeping almost every GLP at the same concentration means I never have to learn new math when moving between them.

LevelThistle44archiveApr 11
↳ replying to @LevelThistle44

8 mg twice a week turned out too strong, so I lowered yesterday's dose to 7 mg for a 14 mg weekly total. Appetite suppression is stronger than needed and there are some lower GI effects, though still manageable. I've dropped four pounds since the earlier post, which is too fast to keep up but fine as a one-time thing.

LevelThistle41archiveApr 11

I went from 2.5 mg tirz every other day to 1 mg reta daily. The sense of fullness after smaller meals returned, but I'm still hungry a lot. I'm starting to wonder if I bought into the reta hype when tirz was already working okay, even though I had stalled for two months. Weight loss has resumed on reta so I'll keep going for now. It's only been a few weeks.

GreenMeadow54archiveApr 11

I'm thinking about trying a bit of reta myself while on 5 mg tirz for maintenance and a lean bulk. The idea is to add 0.5 to 1 mg reta during a short cut phase. Hopefully that lets me avoid cutting calories hard while keeping more muscle. From what others say, tirz mainly handles appetite and reta leans more toward raising metabolism, even though both can do some of each.

SteadyQuill55archiveApr 18

Just so anyone finding this thread later isn't left hanging, I raised reta to 5.5 mg and added back 3.3 mg tirz. The hunger struggle eased and I hit a new low weight yesterday. I'm still aiming a bit lower but not pushing hard, just watching calories and getting to the gym most nights.

WarmAlder42archiveApr 18
↳ replying to @SteadyQuill55

Any bothersome sides from the reta? I had to stop at 2.5 mg twice a week even while still on 8 mg tirz because the hunger from dropping the higher tirz dose stayed bad. Those seven weeks brought higher heart rate, poor sleep, hunger, active gut, and occasional headaches. Once I stopped reta everything settled within two weeks. I'm at a reasonable weight but still want to break a three-month stall.

SteadyQuill55archiveApr 19
↳ replying to @WarmAlder42

None at all. No sides, no particular feelings, nothing noticeable. If I later found out I had been injecting water I'd just think it made sense, though I know that's a common comment and it isn't water.

LevelCinder55archiveApr 19
↳ replying to @QuietAnchor73

That person has no credibility with me either. Another self-proclaimed expert whose only credentials were taken away. Enough said.

RustMarble78archiveApr 19
↳ replying to @SteadyQuill55 (opening post)

Tirz does a much better job stopping hunger. Reta isn't as strong there but I noticed I ate cleaner and picked up some of the other metabolic upsides.

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