A big study of 27 trials (15,584 people) shows that the experimental peptide retatrutide can cut body weight by about 20‑22% after 16 weeks or more, especially at the 8 mg and 12 mg doses. It also shrinks waist size by roughly 16‑17 cm and does this without raising serious side‑effects or causing low blood sugar. The effect is strongest in people without type‑2 diabetes, those who start with a higher BMI, and those who stay on the drug longer. Dual‑ or triple‑agonist drugs like retatrutide work better for weight loss than plain GLP‑1 drugs.

This study aimed to provide evidence-based support and a reference for the efficacy and safety of seven glucagon-like peptide-1 (GLP-1) receptor agonists and polyagonists for weight loss in patients with obesity or overweight through a network meta-analysis. Relevant randomized controlled trials (RCTs) with an intervention duration of at least 16 weeks assessing seven GLP-1 receptor agonists and polyagonists (mazdutide, 6 or 4.5 mg; retatrutide, 12 or 8 mg; tirzepatide, 15 or 10 mg; liraglutide, 3.0 mg; semaglutide, 2.4 mg; orforglipron, 45 or 36 mg; and beinaglutide, 0.2 mg) in patient with obesity or overweight was searched using three databases (Cochrane Library, PubMed, and Embase) from creation to August 30, 2024. The primary outcome was the percentage change in body weight from baseline. Secondary outcomes included changes in waist circumference, hemoglobin A1c, and fasting plasma glucose level from baseline; adverse events, serious adverse events, adverse event withdrawal, and hypoglycemic events. We conducted a frequentist random-effects network meta-analysis to analyze the data extracted from the RCTs using Stata 16.1 software. Twenty-seven RCTs of seven GLP-1 receptor agonists and polyagonists and 15,584 patients were included in the network meta-analysis. In terms of efficacy, compared with placebo, retatrutide 12 mg (-22.10 % in body weight and - 17.00 cm in waist circumference), retatrutide 8 mg (-20.70 % and - 15.90 cm), and tirzepatide 15 mg (-16.53 % and - 13.23 cm) were the three most efficacious treatments for reducing body weight and waist circumference. However, these treatments were less effective in patients with type 2 diabetes mellitus (T2DM). In addition, patients with a high body mass index (BMI) or longer treatment cycles exhibited significantly greater weight loss than those with a low BMI or shorter treatment cycles. In terms of safety, patients without T2DM had a higher incidence of adverse events than those with T2DM. None of the interventions increased the incidence of serious adverse or hypoglycemic events (˂54 mg/dL). There was no significant difference in the incidence of adverse event withdrawal for all interventions in head-to-head comparisons. In addition, disparities in race, BMI, and treatment cycles did not significantly increase the incidence of adverse events. Finally, the sensitivity and publication bias analyses indicated that the basic analysis results were reliable. Retatrutide (both doses) and tirzepatide exhibited superior efficacy compared to other GLP-1 receptor agonists and polyagonists in reducing body weight and waist circumference. Patients without T2DM, those with a high BMI, and individuals undergoing longer treatment cycles demonstrated significantly greater weight loss and reductions in waist circumference. Dual or triple receptor agonists (GLP-1 plus glucose-dependent insulinotropic polypeptide and/or Glucagon receptor) are more effective for weight loss than GLP-1 receptor agonists.