Knowledge Base

Everything we know about peptides, GLP-1s & TRT

Plain-English, science-backed and community-informed. Start with a cornerstone below, jump to a goal, or compare two compounds head to head — every guide links back to the data.

Start here · editor’s picks
CompoundWhat Are Peptides? A Beginner's Guide to the BasicsA plain-English guide to what peptides are: how they differ from proteins and amino acids, the main types with real examples, how they are made, why people use them, and the high-level safety and legal facts you should know first.Read →
Best forBest Peptides for Weight Loss: What the Community Actually Uses (2026)A data-first ranking of the best peptides for weight loss, led by what ~11,400 ProtocolPlus users actually use — tirzepatide, semaglutide, and retatrutide — with honest evidence tiers, trial weight-loss numbers, and which are FDA-approved vs investigational vs research-only.Read →
CompareSemaglutide vs Tirzepatide: Which Wins, and What the Community Actually Switches To (2026)A head-to-head of semaglutide (Ozempic/Wegovy) vs tirzepatide (Mounjaro/Zepbound): trial weight loss, the SURMOUNT-5 direct comparison, tolerability, cost per dose, and first-party data on which one ProtocolPlus users switch to. Honest framing, sourced trial figures, no hype.Read →
CompoundHow to Vet Peptide Quality: Reading a COA, Purity, and Lab TestingA practical guide to peptide purity testing: how to read a Certificate of Analysis (COA), what HPLC purity and mass spec identity actually mean, why third-party testing and endotoxin checks matter, and the red flags of fake or low-quality product.Read →
CompoundGetting Started With Peptides: A Practical Beginner's RoadmapA calm, practical guide to getting started with peptides as a beginner: how to decide if and why, the supplies you actually need, sourcing basics, the one-peptide-at-a-time first protocol, and the baseline safety habits that matter most.Read →

Best peptides for…26

Goal-first guides: the compounds people actually reach for, ranked with the evidence and the community signal.

Foundation 10111

Start here — what peptides are, how they work, sourcing, legality and how to use them safely.

Head-to-head comparisons30

Two compounds, side by side — mechanism, dosing, results and who each one is for.

Side effects & tolerability19

What our community reports, framed honestly against the trial record.

TRT & hormones12

Testosterone optimization, bloodwork and the hormone side of the protocol.

Tracking & performance11

Bloodwork, HRV, sleep and VO₂max — measuring what your protocol actually does.

Compounds by goal

The peptides people reach for, clustered by what they're used for. Browse the full A–Z on the peptide index.

All 49 peptides →

Healing & recovery