The study aims to critically synthesize the mechanisms by which modern pharmacological treatments—sodium-glucose cotransporter-2 (SGLT2) inhibitors, glucagon-like peptide-1 receptor (GLP-1R) agonists, and dual GIPR/GLP-1R agonists—modulate body mass composition, and to analyze the specific implications of these changes (e.g., visceral fat reduction versus lean mass loss) for heart failure (HF) prognosis and management. This evidence concerns the gene SLC5A2 and heart failure.