THE GLP-1 peptides (Glucagon-Like Peptide-1) represents the most studied class of research molecules in the field of obesity and energy metabolism. Large-scale clinical trials have demonstrated reductions in body mass ranging from -15% to -24.2% depending on the target and generation of the peptide. This page presents the main families — mono, dual and triple agonists — their mechanisms of action, the available scientific results, and the products offered by MyPeptide for research.
GLP-1 peptide families under investigation
1. GLP-1 monoagonists — Semaglutide
Le Semaglutide is a human GLP-1 analog with a prolonged half-life. It exclusively targets the GLP-1 receptor (GLP-1R), stimulating glucose-dependent insulin secretion and suppressing glucagon secretion. In the STEP 1 trial (N=1961), Semaglutide 2.4 mg/week induced a body weight reduction of -15.3% over 68 weeks vs -2.6% placebo. It constitutes the first-generation reference for obesity studies.
2. Dual GLP-1/GIP agonists — Tirzepatide
Le Tirzepatide is a unimolecular co-agonist peptide that simultaneously targets GLP-1R and GIPR (Glucose-dependent Insulinotropic Polypeptide receptor). GIP/GLP-1 co-activation produces a synergistic effect on insulin secretion, appetite suppression, and adipocyte lipolysis. In the SURMOUNT-1 trial, Tirzepatide 15 mg/week achieved -22.5% of body weight at 72 weeks, significantly outperforming Semaglutide in indirect comparison.
3. GLP-1/GIP/Glucagon Triple Agonists — Retatrutide
Le Retatrutide represents the third generation: a triple agonist targeting GLP-1R, GIPR, and the glucagon receptor (GCGR). The addition of glucagon agonism amplifies hepatic thermogenesis and basal energy expenditure, in addition to the GLP-1/GIP effects. In the phase 2 published in the New England Journal of Medicine (2023), Retatrutide 12 mg produced a reduction in -24.2% of body weight at 48 weeks, setting a new clinical record in this class.
Mechanisms of action of GLP-1 peptides
Central satiety (hypothalamic pathway)
GLP-1R receptors are highly expressed in the arcuate nucleus and paraventricular nucleus of the hypothalamus. GLP-1R stimulation activates POMC/CART neurons (anorexigenic) and inhibits AgRP/NPY neurons (orexigenic), reducing total caloric intake by 20–35% in preclinical models.
Delayed gastric emptying
Via the vagus nerve and enteric plexuses, GLP-1 delays gastric emptying, prolonging the feeling of postprandial satiety. This effect is measured by gastric scintigraphy: Semaglutide delays emptying by 35% compared to placebo, reducing postprandial blood glucose spikes.
Thermogenesis and energy expenditure (Glucagon effect)
Specific to the triple agonist Retatrutide, GCGR agonism stimulates hepatic thermogenesis (beta-oxidation of fatty acids), increases basal energy expenditure via the activation of beige/brown adipocytes, and promotes hepatic ketogenesis. This additional effect explains the 24.2% superiority observed with Retatrutide versus 22.5% for Tirzepatide.
Adipolysis and remodeling of adipose tissue
The GLP-1/GIP combination activates lipolysis in visceral white adipocytes (preferential reduction of visceral fat), improves insulin sensitivity in peripheral tissues, and reduces inflammatory adipokine markers (IL-6, TNF-alpha, leptin) documented in adipose tissue biopsies.
Scientific comparison
| Molecule | Targets | Weight reduction | Clinical phase | Key study |
|---|---|---|---|---|
| Semaglutide | GLP-1R | -15,3% | FDA/EMA Approved | STEP 1 (NEJM 2021) |
| Tirzepatide | GLP-1R / GIPR | -22,5% | FDA/EMA Approved | SURMOUNT-1 (NEJM 2022) |
| Retatrutide | GLP-1R / GIPR / GCGR | -24,2% | Phase 3 is underway | Phase 2 (NEJM 2023) |
Data from published clinical trials. Percentages represent the average reduction in body weight at the maximum dose studied versus baseline.
In-depth research guides
Find our detailed scientific analyses to further your research on GLP-1 peptides:
- Retatrutide and weight loss — mechanisms and phase 2 results
- Retatrutide vs Tirzepatide vs Semaglutide — a complete scientific comparison
- How the GLP-1 receptor works — molecular mechanisms and implications
- A comprehensive guide to peptides for weight loss in research
- Semaglutide vs Retatrutide vs Tirzepatide — comparative analysis
Retatrutide products available for research
MyPeptide offers the Retatrutide R3 with a purity greater than 99% certified HPLC (Janoshik), exclusively for scientific research in vitro or on animal models.
FAQ — GLP-1 Peptides for Weight Loss
Which GLP-1 peptides are used in obesity research?
The main GLP-1 peptides studied are the Semaglutide (mono-agonist, -15% weight), the Tirzepatide (dual GLP-1/GIP, -22%) and the Retatrutide (triple GLP-1/GIP/Glucagon, -24.2% in phase 2). Retatrutide is currently the most effective as measured in clinical studies.
What is the difference between a mono, dual and triple GLP-1 agonist?
Un mono-agonist Targets only GLP-1 (e.g., Semaglutide). One dual agonist GLP-1 and GIP targets (e.g., Tirzepatide). One triple agonist targets GLP-1, GIP and Glucagon simultaneously (ex: Retatrutide), allowing a combined action on satiety, metabolism and thermogenesis for superior efficacy.
How do GLP-1 peptides work for weight loss?
GLP-1 peptides act through several mechanisms: reduction of appetite via hypothalamic centers, slowing of gastric emptying (prolonged feeling of satiety), improvement of insulin sensitivity, and for the triple agonist, activation of thermogenesis via the glucagon receptor.
Are these peptides available for human consumption?
MyPeptide offers these peptides exclusively for scientific research purposesSemaglutide and Tirzepatide are approved as medications (Ozempic, Mounjaro). Retatrutide R3, offered by MyPeptide, is intended for in vitro or animal research only, in accordance with current regulations.
What is the purity of MyPeptide's GLP-1 peptides?
All MyPeptide peptides have a purity greater than 99% certified by HPLC analysis (Janoshik). Each batch is accompanied by a Certificate of Analysis (COA) which can be downloaded directly from the product page.