Scientific Glossary

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From weakest to strongest: Anecdote/case report → Case series → Cross-sectional study → Case-control study → Cohort study → Randomized Controlled Trial (RCT) → Systematic Review → Meta-analysis. Most research peptides have evidence concentrated in preclinical (animal) studies and case reports, with limited RCT data. GLP-1 agonists (semaglutide, tirzepatide) are exceptional — they have large, multi-phase RCTs placing them at the top of the evidence hierarchy for their specific applications.