Brendan Winters

My retatrutide experiment: 18 pounds in 13 weeks

October 2026

Read this first. Retatrutide is a peptide that is not FDA approved yet. I bought it from a gray-market research vendor and dosed it myself. That means there’s no guarantee of what’s in the vial or how pure it is. This is one guy’s experiment, not advice. Talk to a doctor before you try anything like this.

I think peptides are one of the most exciting new technologies out there. GLP-1 peptides went from a diabetes treatment to one of the biggest stories in medicine in about five years. I like trying new tech early. So this summer I tried the newest one 🧪

Why I tried it

I’m 43 and 6’4”. I played at about 205 to 210 pounds. This summer I was at 233. I train hard, 5 to 6 days a week. I’d tried a bunch of diets and kept hitting the same wall. I wanted to get back near my playing weight.

What retatrutide is

Retatrutide is Eli Lilly’s next peptide after Zepbound. Ozempic hits one hormone target, GLP-1. Zepbound hits two. Retatrutide hits three: GLP-1, GIP, and glucagon. That’s why people call it a “triple agonist.”

The trial numbers are wild:

  • Phase 2 (2023): people on the top dose lost 24.2% of their body weight in 48 weeks. Placebo lost 2.1%.
  • TRIUMPH-4, the first Phase 3 result: 28.7% average weight loss at 68 weeks on the top dose.
  • TRIUMPH-2 and TRIUMPH-3 (July 2026): up to 20.8% in people with type 2 diabetes, and up to 22.6% in people with heart disease, at 80 weeks.
  • Lilly plans to ask the FDA for approval in early 2027. So a legal version is probably still a year or more away.

What I did

One shot a week, under the skin. I started low and stepped up slowly, the way Lilly’s trials do it. This is what I did, not what you should do.

  • Jul 8 and 14: 0.5 mg
  • Jul 20 to Aug 9: 1 mg (4 weeks)
  • Aug 17 to Sep 6: 2 mg (4 weeks)
  • Sep 13: 4 mg (1 week)
  • Sep 20 onward: 3 mg

The 4 mg week was the one bad week. I felt rough, so I dropped back to 3 mg and stayed there.

What I kept doing the whole time:

  • About 200 grams of protein a day, most of it at breakfast and lunch.
  • Lifting 4 days a week, so I’d lose fat and keep muscle.
  • Running and Peloton, training for the Kiawah Island half marathon.
  • Every morning: creatine (10 grams), DripDrop Zero Sugar, essential amino acids, and collagen peptides.
  • Every night: magnesium, L-theanine, and ashwagandha.

The results 📉

  • Weight: 233.2 pounds on July 9. 215.2 pounds on October 6. That’s 18 pounds in 13 weeks, about 1.4 pounds a week.
  • No stall. The scale kept moving the whole time.
  • Resting heart rate: this was my main safety check, because the glucagon part of the peptide can raise heart rate. I started at 52. It stayed at 53 to 55, except for one week at 58 when I went up too fast.

The side effects

  • Way less hunger. Strongest the first week after each dose step, then it eased a bit.
  • Slow digestion. One rough day early on, bloated for hours after a normal lunch. Smaller meals fixed it.
  • Acid reflux. Mild, on and off. Worse right after each step up.
  • Nausea. Only the one week I went up too fast.
  • Muscle cramps. Still working on this one.
  • The weird one: I stopped wanting alcohol. I had one beer over seven hours at a barbecue and didn’t want another 🍺 Researchers are studying GLP-1 peptides for alcohol use now, so I’m not alone.

GLP-1s and living longer

The part that excites me most isn’t the weight. It’s what these peptides might do for health and lifespan.

It’s still early. Most of the longevity data is from people with obesity or diabetes, and a lot of it is observational. Nobody has shown these peptides make healthy people live longer. But it’s the most promising thing I’ve seen.

The honest caveats

  • It’s a sample size of one. No control group.
  • Retatrutide wasn’t the only change. I also started creatine a couple weeks in, and I ramped up my running for the half marathon. So it’s hard to say exactly what did what. My protein and electrolytes stayed the same the whole time.
  • Creatine added a few pounds of water, so my real fat loss is probably a bit better than the scale says.
  • I switched scales in September, so the numbers before and after aren’t a perfect match.
  • I haven’t rechecked my blood work yet. My labs before I started were mostly strong. One cholesterol marker, ApoB, was borderline. The trials show retatrutide lowers it, so my recheck is the number I want most.

What’s next

Goal is 205, about where I played. I’ll get my blood work rechecked and post an update. I’m also looking into a concierge doctor, so a pro can watch the numbers with me 🩺

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