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| 28 Days on Retatrutide |
Retatrutide is the successor to Novo Nordisk's GLP-1 drugs Ozempic/Wegovy (Semaglutide) and Eli Lilly's Mounjaro / Zepbound (Trizepatide). Sometimes it is referred to as GLP-3, as it is a 3rd-generation triple agonist targeting 3 receptors, versus the single receptor targeted by Ozempic.
Retatrutide is NOT approved by the FDA and is currently undergoing research in a Phase III clinical trial called Triumph. It is NOT expected to be approved by the FDA until 2027 or 2028.
Participants in the Retatrutide Triumph trial are losing close to 30% of their weight, among many other health benefits, and the stock price and valuation of Eli Lilly imply the tremendous future success of Retatrutide once approved.
While Retatrutide is NOT approved by the FDA, it is available under a "research only" provision from many companies. It is a grey area that is intended for medical research. That said, if you walk into any weight-loss or wellness clinic, you will find that many are selling Retatrutide and at quite a premium. They may even label it as a "designer weight loss peptide."
You may also have seen Hims and Hers, and other telemedicine firms, selling "compounded" Semaglutide and Trizepatide in the past year. Compounded is another grey area distribution method. Recently, the FDA has been cracking down on compounded drugs, while Robert Kennedy has been promoting the use of Peptides. Hims and Hers, and other telemedicine firms, have stopped selling compounded Semaglutide and Trizepatide in favor of the real versions from Novo Nordisk and Eli Lilly.
Initially, I was planning to start Retatrutide in June of 2026, but the FDA cracking down on compouders spooked me into moving that up to March. Some people in the Retatrutide community were also stocking up, as it can be safely stored in a refrigerator for up to 2 years.
It is my understanding that most of the Retatrutide is coming from China with very little being produced in the US. That isn't necessarily bad. The Chinese even have key patents and processes in play to manufacture Reta. But legitimacy is always a concern. There are real risks for things like endotoxins.
Most sellers or resellers of Retatrutide, including Evolve Peptides, will provide a Certificate of Authenticity to verify the product's authenticity and purity. Some won't even use the word Retatrutide on their website, but will mark the product with something like "GLP-R" where the R stands for Reta. If you hear the word "Ratatouille," this is slang for Retatrutide. Either way, the product is sent to labs for purity and quantity testing, as well as for testing for contaminants such as endotoxins. Be aware: you can always fake a certificate of authenticity!
That said, people are going to be people and find a way even if you tell them NOT to. I did!
Personally, I ordered a 15mg vial of the Retatrutide peptide from Evolve Peptides based on a recommendation from a very well-known biohacker and triathlete, and took the plunge. NONE of this is Medical Advice BTW. This is just my experience!
In 28 days (Mar 15-Apr11) I lost 22lbs. Yes, I'm sure a ton is water weight, but there was plenty of weight loss as well. The results are simply undeniable. In addition, as a former pro triathlete, I pretty much stopped exercising in favor of landscaping instead. Now, landscaping can be a lot of work, but I had been told you have to be careful how much cardio you do on reta because weight just melts off. I guess it did anyway.
Protocol
For reference, the official Eli Lilly Triumph study is starting participants on a single dose of 2mg as a once-weekly injection, gradually titrating them up to 12mg.
I decided to go with a 1mg injection on Saturday night, and 1mg injection Tuesday or Wednesday for a total of 2mg weekly.
Keep in mind that vials are ONLY guaranteed sterile for 28 days. I did end up going past that date, but keep this in mind. You don't want a vial that is too big to get through. Vials also must be kept refrigerated. They risk both bacterial contamination and the peptides themselves breaking down and becoming ineffective. I have heard that retatrutide will last up to 60 days, but any reconstituted peptide is still only good for 28 days, based on standard medical guidelines for sterility.
Given my 2mg a week injection, I really should have bought a 10mg bottle.
If I had planned to do 1mg a week, then a 5mg bottle would have been sufficient.
Vials are usually overfilled, so if you get a 10mg vial, it might contain 10.13mg, but you are also never going to get every last drop out of the vial.
Supplies I needed other than Retatrutride
It isn't just the Retatrutide that I needed. I also needed...
- Disposable Gloves 100 count - Glove up for sterility.
- Sterile prep pads - Used to wipe the injection site and the tops of both the peptide vial and the reconstitution solution vial.
- Reconstitution Solution (From Evolve) - Sterile Bacteriostatic water vial, which I draw from and inject into the peptide vial to reconstitute the Retatrutide. I ordered my solution from Amazon, but Amazon has pulled all its reconstitution solution recently. You may want to order extra Bacteriostatic water. The 28-day period only applies to opened bacteriostatic water, so you can store it for longer unopened. It is inexpensive, and it is nice to have some backup in case you mess something up.
- 1ml Syringes 31g 1/4 6mm 20 Pack - used to inject myself in the left or right abdominal belly fat with peptides drawn from the peptide bottle. A 31-gauge needle is tiny. You don't even feel it. 31-gauge is a happy medium sweet spot. 32mm is too small and fragile, 30mm is too thick and can bruise. Also, these are individually wrapped. 6mm in length is the sweet spot for the tip length IMHO.
- 2.5ml Syringes 25ga 25pack - Used to draw the bacteriostatic water and inject it into the peptide vial to reconstitute the peptide. You only do this once per vial at the very beginning. Then you draw from the peptide bottle with smaller needles.
- Collagen (optional) - Given the lower caloric intake on Retatrutide it is important to supplement the building blocks for healthy skin and hair growth. I buy my Collagen from Costco, but this is the brand I use.
Reconstitution of Retatrutide
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| Reta Cheat Sheet |
In my case, because I had 15mg of Retatrutide Peptide, I reconstituted it with 1.5ml of reconstitution solution. In essence, this is .1ml per mg, which helps keep the math easy when drawing from the vial. In this case, for my 1mg injection, I would withdraw .1ml (10 units on the syringe) for each shot. This .1ml is my 1mg of Retatrutide
If I wanted a 2mg dose, I would need 20 units (.2ml). The 1ml syringe has a total of 100 unit capacity.
Ultimately, this is what works for me.
I watched many YouTube videos for best practices in reconstitution. I would recommend watching a few, preferably the longer ones that don't skip minor details and gotchas.
Coupon Codes
I have only ever used Evolve Peptides. If you follow my editorial policy from my pro triathlete days, I only use and recommend products that I actually use.
15% off Evolve Peptides Coupon Code - Use code thomasgerlach
Side Effects
Some people have asked what side effects I have had. Side effects are similar to semaglutide and tirzepatide. I will only list the side effects I have had, which correspond to those listed in the Phase 2 and Phase 3 Eli Lilly Retatrutride studies.
1) Nausea - early on, I did have some low-grade nausea. It wasn't bad, but the food didn't even look appealing. Nothing like you might have with, say, the flu.
2) Diarrhea - early on, I did have some mild diarrhea. That has mostly corrected. I did have one night where I got up to use the bathroom, which is highly unusual. In general, eating less affects how often and when you have bowel movements.
3) Resting heart rate - my resting heart rate did creep up from roughly 44 to about 50. I will mention again that I did not exercise during this period, except for 2 short runs, which is far less than I would usually do.
4) I did not notice any sleep abnormality like some people have. I do pay particular close attention to my sleep and creating a good sleep environment that is dark and cool. I could easily see how Retatrutide makes one run extra hot at night. I also found myself probably waking up less to pee in general than I normally would.
What I noticed
- Food Noise - I would never have understood what food noise was before Retatrutide. The concept makes complete sense now. Basically, you just never think about food. It could actually be dangerous because sometimes you have to remind yourself to eat.
- Eating can be a chore - It brings me back to my athlete days when I was consuming 5000+ calories every day. Sometimes I make a bowl of oatmeal midday, and I struggle to eat it. It might take me an hour, rather than 15 minutes previously.
- Food Bill - Food bill is way down. It is noticeable!
- Snacks - I don't keep a lot of snacks in the house, but 2-3x a week I would go to Publix for some snacks. In the entire first month, I never went to Publix. When I finally did walk into Publix, it felt foreign.
- Energy Levels - Energy levels were normal or even above normal. As a quintessential example, I would go out on a Saturday and landscape all day in 80-degree Florida heat - we're talking like 8-10 hours straight. I would drink a few glasses of water and have a bowl of frozen mango, maybe midday, but I never got hungry, and I still had energy. I have done this numerous times before without Retatrutide, and I would get famished and really start slowing down towards the end of the day. I never hit a wall with Retatrutride.
I firmly believe my response to Retatrutide was in due in part to the glucagon component. Retatrutide is known as GLP-3 as it is a triple agonist molecule, whereas Semaglutide is a single, and Trizepatide is a double. Only Retatrutide targets glucagon, which helps break down fat and mobilize it as fuel.
- Productivity - My general productivity has gone through the roof. This may be a combination of factors, but the lack of food noise may be contributing to this. We take for granted how often food breaks disrupt our workflow. There may also be some placebo effects here, just from trying to be better in general.
- Hair growth - hair growth has rapidly declined, most likely due to the lack of nutrients. I need to stay on top of my collagen intake, which I add to my morning coffee. I really noticed the slower growth in facial hair.
Why Retatrutide and Not Semaglutide or Trizepatide?
According to data from Q3 2025, 12.4% of US adults are on a GLP-1. I could have chosen Semaglutide (Ozempic) or Tirzepatide (Wegovy), Evolve sells both as well, but I chose to go with Reta as the 3rd generation, triple-agonist, versus the single agonist (Semaglutide) or double agonist (Tirzepatide).
GLP-1s have been around for decades, but each one keeps getting better. They are working on 4th and 5th generations as well. Reta is widely available and offers the best-in-class weight-loss. The cost difference is minimal. I went with best-of-breed, and I was comfortable taking "research only" peptides.
That said, I would have no problems switching to Tirzepatide. I know many people who are on Tirzepatide and have had great results as well with minimal side effects.
I suspect there is a good chance of crackdowns on Retatrutide coming, and I would certainly switch to Tirzepatide or Semaglutide if that happened. Obviously, Eli Lilly and Novo Nordisk want to sell as much as they can. Both compounding pharmacies and research-only peptide suppliers are seeing sales decline.
