Retatrutide weight loss claims: what the science actually shows

What did @reagos_fitness actually say?

He's four weeks into retatrutide and two weeks into tesamorelin, reports roughly half a pound of weight loss this week versus more in prior weeks, and says his energy and strength are unchanged. The most interesting claim is almost a throwaway: he wants to eat junk food but simultaneously doesn't want to, and finds that psychologically strange. He frames the slow week casually, saying "everything is being Gucci."

He's also at a self-reported 4 milligram dose and hints he might increase it. That last part is worth flagging immediately, because dose escalation on a triple agonist peptide is not a casual decision, and he treats it like adjusting his pre-workout scoop.

Does the science back this up?

The appetite suppression description is actually one of the more scientifically coherent things in the video, even if he can't quite articulate it. The weight plateau after rapid early loss is also textbook GLP-1 pharmacology. The strength retention claim is plausible but unverifiable from this video alone.

Retatrutide is a triple agonist hitting GLP-1, GIP, and glucagon receptors. The Phase 2 trial (Jastreboff et al., 2023, New England Journal of Medicine) showed dose-dependent weight loss of up to 24.2% body weight at 48 weeks at the 12 mg dose. Early weeks showed faster loss that slowed as patients approached a new set point, which matches his experience. The appetite effect he describes, wanting food but not wanting it, maps to what researchers call reduced reward salience for palatable foods, an effect documented in GLP-1 receptor agonist literature (ten Kulve et al., 2016, Diabetes Care).

What did they get wrong (or right)?

He got the appetite description surprisingly right, even if his language was imprecise. The plateau framing is also defensible. What he got wrong, or at least dangerously casual about, is the dose discussion.

Self-titrating a GLP-1/GIP/glucagon triple agonist without clinical oversight is a real risk. Retatrutide is not FDA-approved for any indication as of this writing. Compounded versions are not equivalent to any brand-name product, and the Phase 2 data showing that higher doses produced more side effects, including nausea, vomiting, and injection site reactions (Jastreboff et al., 2023), is not something to wave off with "might bump that up soon, might not." He also conflates retatrutide and tesamorelin as a casual stack, and those are two very different mechanisms. Tesamorelin is FDA-approved specifically for HIV-associated lipodystrophy, not general body composition optimization, and stacking it with a triple agonist is outside any studied protocol.

What should you actually know?

A few things matter here beyond the fact-check of one guy's TikTok. Retatrutide is still investigational. The trial data is promising but comes from controlled settings with medical monitoring, not self-directed use filmed for social media. The appetite suppression effect he describes is real and documented, but it does not mean the compound is safe or appropriate for general fitness use.

The tesamorelin combination deserves its own conversation. Tesamorelin raises IGF-1, which has downstream effects on glucose metabolism. Pairing that with a glucagon receptor agonist that itself affects glucose homeostasis is not a stack anyone has studied in healthy, recreationally active adults. If you are curious about either compound, that curiosity should start with a licensed clinician who can review your metabolic labs, not a week-five recap video. The slow week on the scale is not a red flag. The casual dose-bump discussion is.

The bottom line on stacking retatrutide and tesamorelin

No published human data exists on this specific combination in a fitness or body composition context. Tesamorelin's approval is narrow. Retatrutide has no approval at all. The interaction between glucagon receptor agonism and GH-releasing hormone analogs on glucose, lipid metabolism, and cardiovascular parameters is not something you should be figuring out through trial and error on week five of a TikTok series.

• Retatrutide Phase 2: mean weight loss 17.5% at 24 mg equivalent dose over 48 weeks, with dose-dependent adverse events (Jastreboff et al., 2023, NEJM)
• Tesamorelin FDA indication: HIV-associated lipodystrophy only, not general fat loss
• GLP-1 agonists reduce reward-driven eating via CNS pathways, which likely explains his psychological discomfort around food cravings (ten Kulve et al., 2016)
• No peer-reviewed data exists on retatrutide plus tesamorelin co-administration in any population