Peptide claims from a bodybuilding TikTok: what holds up?

What did @kodi_dyel actually say?

Kodi ran through two lists: one for cutting, one for bulking. For fat loss, he named clenbuterol, T3, T4, albuterol, tirzepatide, retatrutide, semaglutide, GW-501516 (Cardarine), AOD-9604, and L-carnitine. For bulking, he pointed to CJC-1295 with ipamorelin, IGF-1, PEG-MGF, and MK-677, while noting he prefers real growth hormone over MK-677. He also teased an upcoming peptide company with "crazy blends that nobody else has." Throughout, he acknowledged some of these aren't technically peptides and framed everything as personal preference based on years of use.

One thing worth flagging immediately: several compounds on his cutting list, specifically clenbuterol, T3, T4, and retatrutide, are not peptides at all. Clenbuterol is a beta-2 agonist. T3 and T4 are thyroid hormones. Lumping these together under "favorite peptides" misrepresents what these compounds are and how they work.

Does the science back this up?

Some of it does, some of it doesn't, and the gaps matter. The GLP-1 receptor agonists he mentioned, semaglutide and tirzepatide, have the strongest evidence base of anything on either list. Retatrutide is real but still in phase 2 trials. The bulking peptides have a thinner research record in healthy humans.

Semaglutide's weight loss data is well-established. Wilding et al. (2021, NEJM) showed 14.9% mean body weight reduction over 68 weeks in adults with obesity. Tirzepatide outperformed that in the SURMOUNT-1 trial (Jastreboff et al., 2022, NEJM), with up to 22.5% weight loss at the highest dose. These are legitimate findings. Retatrutide, a triple GIP/GLP-1/glucagon receptor agonist, showed up to 24.2% weight reduction in a phase 2 trial (Jastreboff et al., 2023, NEJM), but it is not approved anywhere as of this writing.

CJC-1295 with ipamorelin stimulates growth hormone release. The combination is widely used in anti-aging and performance contexts, but controlled human trials in healthy adults are scarce. IGF-1 and PEG-MGF have even less clinical support outside of specific medical conditions like growth hormone deficiency.

What did they get wrong (or right)?

Credit where it's due: he correctly identified that MK-677 and GW-501516 are not peptides, and he's right that real growth hormone has a more established pharmacological profile than MK-677 as a secretagogue. He also didn't overclaim, largely framing things as personal use rather than guaranteed results.

Where he went wrong: mixing thyroid hormones and beta-2 agonists into a "peptide" conversation without distinguishing their risk profiles is irresponsible for a creator with a platform. Clenbuterol is not approved for human use in the United States and carries documented cardiac risks, including tachycardia and arrhythmia (Goldstein et al., 1998, Chest). GW-501516 was abandoned by GlaxoSmithKline after it caused cancer in multiple animal tissue types in preclinical studies. Presenting it casually alongside AOD-9604 and L-carnitine, without that context, is a genuine problem.

AOD-9604 is sometimes marketed as a fat-loss peptide, but it failed to demonstrate significant weight loss versus placebo in its phase 3 clinical trial (Heffernan et al., 2001, J Pediatr Endocrinol Metab). Presenting it as a go-to is not supported by the evidence.

What should you actually know?

The legitimate compounds on his list, semaglutide, tirzepatide, and to a lesser extent the GH-releasing peptides, require medical supervision, proper diagnosis, and ongoing monitoring. They are not interchangeable, and none of them are without side effects. GLP-1 agonists carry real risks including nausea, pancreatitis, and potential thyroid C-cell effects based on rodent studies, though human thyroid cancer risk remains under investigation.

The bigger issue here is the framing. When an IFBB pro with 15,000 viewers casually lists clenbuterol and retatrutide in the same breath as L-carnitine, it normalizes a risk hierarchy that doesn't reflect reality. Retatrutide has no approved indication. Clenbuterol is outright banned for human use by the FDA. These distinctions matter.

If you are interested in any peptide or weight-loss compound, the right path is a licensed provider who can review your labs, health history, and goals. A TikTok list, even from someone with real-world experience, is not a clinical assessment.