# Metabolic & Weight Research Peptides: What the Record Shows After the Last Dose

> Metabolic & Weight Research Peptides — What the Trials Recorded After the Last Dose — Brand My Peptides — A reference desk on Metabolic & Weight research peptides — semaglutide, tirzepatide and retatrutide — read through discontinuation: every headline weight figure was measured on treatment, and separate withdrawal designs measured what happened after it stopped.

**METABOLIC & WEIGHT RESEARCH / DISCONTINUATION**

Three incretin-class peptides, three headline weight figures — and one property those figures share. Each was measured while treatment was still running. This desk reads the literature from the other end.

### [Semaglutide](/semaglutide)

![Semaglutide research illustration](images/semaglutide.webp)

The lead entry on this desk, and the compound with the deepest record on both sides of the question. A GLP-1 receptor agonist with completed weight, cardiovascular and kidney outcome trials — and the only one here whose own trial programme includes both a randomised withdrawal design and an off-treatment extension.

### [Tirzepatide](/tirzepatide)

![Tirzepatide research illustration](images/tirzepatide.webp)

A dual GIP and GLP-1 receptor agonist that outperformed semaglutide on weight in a head-to-head trial, and whose own withdrawal study reported the same divergence the class keeps producing: the arm that kept receiving drug kept losing, and the arm switched to placebo did not.

### [Retatrutide](/retatrutide)

![Retatrutide research illustration](images/retatrutide.webp)

An investigational triple agonist at the GIP, GLP-1 and glucagon receptors, carrying the largest Phase 2 weight figure in the class and the thinnest cessation record of the three: no withdrawal arm has reported, and durability after stopping is listed among its explicit unknowns.

## The short version

Three peptides sit on this desk: [semaglutide](/semaglutide) (Ozempic, Wegovy), [tirzepatide](/tirzepatide) (Mounjaro, Zepbound) and [retatrutide](/retatrutide), an investigational compound with no brand name. All three copy gut hormones that signal to the brain that a meal has arrived, and all three lower body weight mostly by lowering how much food is eaten.

Each one has a famous number attached to it. Every one of those numbers was recorded while participants were still receiving the drug, with the intervention still running.

A different set of studies asked the other question: what the scale does after the last dose. Their answer, repeated across compounds and across designs, is that weight returns. Not instantly, not identically for every participant, and not always all of it — but enough that the literature describes these compounds as ongoing treatment rather than a cure.

That is the whole subject of this desk. Nothing here is medical advice, and no quantity described on any page is a recommendation for any person.

## Every headline number is an on-treatment number

It is worth reading the famous figures with their timestamps attached, because the timestamp is the part that gets dropped in summary.

In the STEP 1 randomised trial, once-weekly subcutaneous semaglutide 2.4 mg produced a mean body-weight change of **-14.9% from baseline to week 68**, against -2.4% with placebo, in adults with overweight or obesity and without diabetes [4]. In SURMOUNT-1, a 72-week trial in 2,539 adults with obesity and without diabetes, once-weekly tirzepatide produced mean weight changes **at week 72** of -15.0%, -19.5% and -20.9% at the three doses studied, against -3.1% with placebo [10]. In the SURMOUNT-5 head-to-head trial in 751 adults, tirzepatide reached -20.2% and semaglutide -13.7% **at week 72** (P<0.001) [1]. In a 48-week Phase 2 obesity trial, once-weekly retatrutide at 12 mg produced a mean **-24.2% body-weight change** against -2.1% with placebo [15].

Each of those is an endpoint measured under continuing exposure. None of them is a statement about what a participant weighs a year after the injections end, and none was designed to be. Read as a durable property of the compound, a week-68 figure says something the trial never tested.

## How the cessation evidence was actually built

Three study designs carry the discontinuation question, and they are not interchangeable.

**The randomised withdrawal design.** Every participant receives the active compound during a run-in period, and only then are they randomised — some continue, others switch to placebo. Because both groups have already lost weight, the design isolates what continuation is doing. A semaglutide withdrawal study reported regain after participants moved to placebo, while those continuing treatment maintained a different course. A tirzepatide withdrawal study used the same logic and likewise reported divergence between continuation and placebo-switch arms.

**The off-treatment extension.** Here the trial keeps following participants after treatment and the accompanying trial intervention are withdrawn. The semaglutide extension reported substantial regain, with cardiometabolic improvements moving back toward baseline alongside the weight. Pooled withdrawal analyses summarized in the composed research record describe regain as related to the amount initially lost.

**The design that has not reported yet.** For retatrutide there is no withdrawal arm in the published record. Durability after discontinuation is listed among the unknowns, alongside long-term safety and cardiovascular and renal outcomes; the review in this desk's source set describes the pivotal programme as ongoing [12].

The withdrawal evidence is kept qualitative here because the numbered source list contains no direct withdrawal publication. That boundary matters: an efficacy paper should not be made to stand in for a separate discontinuation result.

## What a research peptide is, and what this desk is not

A peptide is a short chain of amino acids — the same building blocks as a protein, in a much shorter run. The three compounds here are engineered analogues of naturally occurring gut hormones, redesigned so they remain available far longer than the hormones they copy. Each carries a fatty-acid arm that binds albumin in the blood, an engineering choice that supports extended exposure. Semaglutide is built from a GLP-1 analogue; tirzepatide and retatrutide use GIP-based backbones. Reviews and clinical references describe that long-acting pharmacology for the three entries [5][8][12].

Two members are approved prescription medicines with labelled indications. The third, retatrutide, is investigational and approved by no regulator; every figure attached to it comes from a clinical trial rather than from approved labelling.

This desk is a reading of published literature and nothing else. It names no supplier, quotes no price, compares no vendor and publishes no preparation, reconstitution or administration procedure. The name on the domain is a domain name: nothing here is branded, white-labelled, formulated or sold. Questions about a prescription belong with the clinician who wrote it, and questions about an investigational compound belong with the trial running it.

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Brand My Peptides is a reference desk on the metabolic-peptide literature: it records what each trial measured, at what point in the trial, and what the withdrawal arms recorded afterwards — it brands nothing, sells nothing, prescribes nothing and advises no one.