Peptides for Fat Loss

Mechanism 01

Incretin-Mediated Appetite Suppression

GLP-1 receptor agonists (semaglutide, liraglutide) and dual agonists (tirzepatide) reduce food intake through central appetite suppression and delayed gastric emptying, producing substantial and sustained caloric deficits.

Mechanism 02

Multi-Receptor Hormonal Agonism

Investigational compounds like retatrutide engage GLP-1, GIP, and glucagon receptors simultaneously, potentially amplifying metabolic effects beyond single-receptor approaches. Phase 2 data shows promising weight reduction.

Mechanism 03

GH-Fragment Lipolysis

AOD-9604 and Fragment 176-191 were designed to isolate the fat-metabolizing portion of growth hormone without its growth-promoting effects. Despite theoretical appeal, controlled human trials have not demonstrated significant fat loss.

Best Evidence for Fat Loss

FDA-approved GLP-1 agonists represent a paradigm shift in pharmacological fat loss, with consistent and clinically meaningful results across multiple large trials. The evidence gap between approved incretin therapies and research-only GH fragments is among the largest in peptide research.

Strongest Individual Compound

Semaglutide and tirzepatide for clinically significant fat loss in adults with obesity. Liraglutide for moderate fat loss with the longest post-market safety record in the GLP-1 class. These are the only peptides with robust, replicated human evidence for fat reduction.

What This Category Cannot Do

GLP-1 agonists produce weight regain upon discontinuation in most patients. Retatrutide Phase 3 data is pending. AOD-9604 and Fragment 176-191 failed human efficacy trials and should not be considered evidence-based fat loss interventions. Fragment 176-191 and AOD-9604, both Animal Studies-classified compounds, should not be treated as equivalent to FDA-approved agents such as semaglutide or tirzepatide in terms of evidence strength or regulatory status.

PSI Reading of the Evidence Gap

Fat loss research covers the full spectrum from FDA-approved medications with large trial programs to investigational compounds at earlier stages. GLP-1 receptor agonists have the most established fat loss evidence through body composition data from large randomized controlled trials. GH-fragment compounds have not demonstrated clinical efficacy for fat loss in controlled human trials. Evaluating compounds on body composition data quality rather than mechanism alone gives the most accurate picture of fat-specific evidence in this category. Among the GLP-1 class agents on this page, tirzepatide and semaglutide carry the strongest evidence classifications, both holding FDA Approved status within PSI's framework. A direct head-to-head analysis of these two agents is available in the semaglutide vs tirzepatide comparison.