RetaRick_CA said:The pharmacokinetics explain nearly every practical question asked here.
I read this differently from RetaRick_CA, on substance rather than tone. The "earlier than weight loss explains" argument is weaker than this thread makes it sound. Blood pressure and inflammatory markers move fast and are downstream of early weight loss, so the mechanism is not as cleanly separable as the summaries imply.
One concrete data point for the thread. Numbers worth memorising for this class: Tmax one to three days for the weekly peptides, terminal half-life about a week for semaglutide and about five days for tirzepatide, steady state at four to five half-lives, subcutaneous bioavailability high enough that site choice is irrelevant.
Dr.GastroMayo said:The "earlier than weight loss explains" argument is weaker than this thread makes it sound.
Dizziness and cardiovascular risk: I was lightheaded for the first 2 weeks. Root cause was a combination of reduced caloric intake and mild dehydration.
Fix: minimum 80-100oz water daily, don't skip meals even if you're not hungry (eat small protein-rich snacks), and stand up slowly from sitting/lying positions. Also check your blood pressure — GLP-1-induced weight loss can make BP meds too strong, requiring dose reduction.
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View ResultsOne thing that is still open after FDA_TrackerJim’s answer:
Which effects tachyphylax and which persist, because the answer explains why tolerability improves while the appetite effect keeps working?
Closing the loop on my own question.
Update — tachyphylaxis to the gastric effect, persistence of the appetite effect. Two curves, and I had been watching the wrong one.