Compound tirzepatide for weight loss: what TikTok gets wrong

What did @catreaamcknight actually say?

She announced a starting weight of roughly 412 pounds and said she was beginning compound tirzepatide at a dose she described as "2.5" administered in "25 units" via subcutaneous injection into the abdomen. She noted no burning or unusual sensation after injecting, and she plans to share follow-up updates. That is essentially the full scope of medical content in the video.

To be fair, she did not make sweeping therapeutic promises. There were no claims about curing diabetes, no before-and-after guarantees, and no specific weight-loss targets stated. The video is a personal diary-style post, not a clinical explainer. Still, a few details in that short transcript are worth examining carefully.

Does the science back this up?

The underlying drug class does have real evidence behind it. Tirzepatide, a dual GIP and GLP-1 receptor agonist, is among the most studied weight-loss agents currently available. The data is legitimate and substantial.

The SURMOUNT-1 trial (Jastreboff et al., 2022, New England Journal of Medicine) found that participants taking the highest dose of tirzepatide lost an average of 20.9% of body weight over 72 weeks, compared to 3.1% on placebo. That is a real, peer-reviewed finding. For someone starting at 412 pounds, a 20% reduction would represent more than 80 pounds, which is clinically meaningful for cardiovascular risk, joint health, and metabolic markers. Tirzepatide also showed improvements in blood pressure, lipids, and glycemic control in that same trial.

What the science does not confirm is that compounded tirzepatide produces identical outcomes to brand-name Zepbound or Mounjaro. Compounded formulations are not FDA-approved and have not been tested in large-scale trials. That distinction matters.

What did they get wrong (or right)?

The dosing language is slightly muddled and worth flagging. She said "2.5" and then clarified "25 units," which suggests she is drawing 25 units on an insulin syringe. Depending on the concentration of the compounded formulation, 25 units on an insulin syringe may or may not correspond to a 2.5 mg dose. Compounded tirzepatide comes in varying concentrations, and the math matters. This is not necessarily an error on her part, but it is a reason why patients should confirm their dose in milligrams, not just units, with their prescribing provider.

She got the injection site right. Subcutaneous abdominal injection is a well-established and appropriate site for GLP-1 class medications, consistent with clinical guidance from prescribing information for tirzepatide products.

She also correctly implied that a first injection should not cause dramatic burning or pain, which is generally true for properly formulated subcutaneous peptides. Significant injection-site pain can be a sign of improper formulation or incorrect technique, so her uneventful experience is actually a reasonable data point.

What should you actually know?

Compounded tirzepatide is not the same product as FDA-approved Zepbound or Mounjaro. This is not a minor regulatory footnote. The FDA does not verify the potency, sterility, or bioavailability of compounded formulations. In 2024, the FDA issued warnings about dosing errors with compounded semaglutide and tirzepatide, specifically because unit-based dosing on insulin syringes led to patients taking incorrect amounts. A 2023 analysis published in JAMA Internal Medicine (Carvajal et al.) identified compounding quality as an ongoing patient safety concern in the GLP-1 space.

For someone at 412 pounds, tirzepatide does represent a pharmacologically reasonable intervention. But weight at that level also means higher risk for side effects including gastroparesis-related complications, cardiovascular monitoring needs, and potential drug interactions. Starting any GLP-1 class medication at higher body weights should happen under active medical supervision, not just a telehealth prescription and a TikTok update.

• Always confirm your dose in milligrams with your provider, not just in syringe units.
• Compounded peptides should come from an FDA-registered 503A or 503B pharmacy.
• Report any unusual injection-site reactions or gastrointestinal symptoms to your prescriber promptly.