This week, the question filling every GLP-1 forum that no study has ever touched: why does appetite suppression seem to fade in the two weeks before your period? Plus: the FDA peptide announcement that went viral and was almost entirely misread.

Two things, both worth your time. Let's go. ☕

THE BIG ONE

Why your GLP-1 goes quiet two weeks before your period

"It works beautifully for two weeks. Then the food noise comes roaring back, then my period shows up, then it works again. Am I imagining this?"

That question, in some form, is one of the most repeated in GLP-1 forums right now. You are not imagining it. Here is what the research actually says, in three parts.

THE LUTEAL PHASE IS HUNGRY, MEDICATION OR NOT

In the roughly two weeks between ovulation and your period, progesterone climbs and estrogen dips. Across decades of controlled feeding studies, women eat more in this phase, on the order of a few hundred extra calories a day, with a documented tilt toward carbohydrates and sweets. It is one of the more replicated findings in nutrition science. It is not willpower. It is endocrinology.

ESTROGEN AND GLP-1 ARE ON THE SAME TEAM

In animal studies, estrogen strengthens GLP-1 signaling in the brain regions that govern appetite. Researchers have built estrogen-GLP-1 hybrid molecules that outperform either compound alone, in rodents. In humans, women in the pivotal weight-loss trials lost more on average than men did. So when estrogen drops after ovulation, it is biologically plausible that the medication's satiety signal drops with it. Plausible is the key word. Nobody has measured it directly.

THE WEEKLY RHYTHM CAN STACK ON TOP

Semaglutide (Wegovy and Ozempic, both FDA-approved) and tirzepatide (Zepbound and Mounjaro, both FDA-approved) are injected once a week. Many women describe appetite creeping back on days five through seven. If your shot day and your luteal phase overlap the wrong way, two dips land in the same week. Observed constantly. Studied never.

WHY IT MATTERS

The trials that got these drugs approved were majority women. Not one reported results by cycle phase. The protocols were never tailored to how women's bodies actually work across a month. That is the gap this newsletter will keep coming back to.

THE FEMALE DATA GAP

The studies were full of women. The analysis was not. That is the gap in one sentence, and it is the one we will keep coming back to.

DEINFLUENCED

WHAT THE EVIDENCE SAYS

On July 23 and 24, an FDA advisory committee reviewed seven peptides that some pharmacies have been compounding for years: BPC-157, KPV, TB-500, MOTS-c, DSIP, Semax, and Epitalon. The committee voted narrowly to recommend six of them for a list that would allow licensed compounding pharmacies to prepare them by prescription. DSIP was voted down.

Three things the headlines dropped:

An advisory vote is advice. The FDA is not bound by it and has not acted on it. Nothing changed at any pharmacy counter. The FDA's own scientists recommended against all seven compounds, citing gaps in safety and effectiveness data. The committee overruled the staff, which is unusual enough that it made national news on its own. And "compounded by prescription" is not "FDA-approved." Compounded drugs skip the clinical trials, the approved labeling, and the manufacturing oversight that approved drugs go through. None of this touches the vials sold online as "research use only." Those are exactly as unregulated today as they were in June.

For the record: in the weeks since the vote, a Texas pharmacy recalled compounded peptides over endotoxin contamination and a peptide vendor was sentenced to nearly six years in prison. The market got louder. It did not get safer.

ASK A CLINICIAN

Not worried, but yes, worth raising. Losing weight quickly on a smaller appetite changes the things a routine lab panel is designed to catch: kidney and liver markers, blood sugar, lipids, and the nutrients that can become harder to hit when you are eating less, like iron, B12, and vitamin D.

There is no single required panel, and what makes sense for you is a conversation between you and your prescriber. Asking about baseline labs and a follow-up recheck is completely reasonable, and most prescribers will say yes without hesitation. If yours says no, asking why is a fair next question.

Mais, PharmD

Medical Reviewer, Pep in Her Step

ON THE RADAR

This issue was medically reviewed by Mais, PharmD.
Pep in Her Step is education, not medical advice.
Talk to your prescriber before doing anything peptide-shaped.
We don't sell peptides and never will.

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