The Clinical Weight Loss
Revolution, Explained.
GLP-1 receptor agonists have produced more clinically significant fat loss than any compound in the history of obesity medicine. This is the complete guide — mechanism, compound selection, titration, and protocol design.
GLP-1 Class Compound Comparison
Semaglutide
GLP-1 receptor agonist
Receptors
1
Half-life
~7 days
Start dose
0.25mg/wk
Brand equiv.
Ozempic / Wegovy
Tirzepatide
GLP-1 + GIP dual agonist
Receptors
2
Half-life
~5 days
Start dose
2.5mg/wk
Brand equiv.
Mounjaro / Zepbound
Retatrutide
GLP-1 + GIP + Glucagon triple agonist
Receptors
3
Half-life
~6 days
Start dose
1mg/wk
Brand equiv.
Pipeline — Eli Lilly
CagriSema
GLP-1 + Amylin dual pathway
Receptors
2
Half-life
~7 days
Start dose
0.25mg/wk
Brand equiv.
Pipeline — Novo Nordisk
How Incretin Peptides Drive Fat Loss
Six distinct biological signals — each targeting a different element of the fat loss equation.
Hypothalamic GLP-1R activation
Reduces appetite, food-seeking behavior, and meal size by 20–40%
Gastric emptying delay
Food moves through the stomach 30–50% slower — extending satiety windows significantly
GIP receptor activation (Tirze/Reta)
Directly targets adipose tissue and amplifies fat oxidation beyond GLP-1 signaling alone
Glucagon receptor (Retatrutide only)
Raises basal metabolic rate by 5–8% — attacks fat loss from the energy expenditure side
Amylin pathway (CagriSema only)
Separate satiety signal via calcitonin receptor — additive to GLP-1, distinct mechanism
Insulin sensitization (all)
Improves insulin sensitivity, fasting glucose, and lipid panels as secondary benefits
The Iron Rule of GLP-1 Titration
Every GI side effect (nausea, vomiting, delayed gastric emptying discomfort) from GLP-1 class peptides is dose-dependent and preventable with correct titration. Slow titration is not optional — it is the protocol.
Never skip dose steps
Each step conditions GI receptors before you move up
Stay at each dose 4 weeks
Tolerance develops over 3–4 weeks at each level
Side effects = go back down
If nausea is persistent, return to the previous dose for 2 more weeks
11 GLP-1 class fat loss peptides
From starter semaglutide to advanced triple-agonist retatrutide
GLP-1 S 5mg
GLP-1 receptor agonist — clinically proven appetite reduction and sustainable fat loss
GLP-1 S 10mg
Double-vial supply of semaglutide — ideal for extended fat loss protocols
GLP-1 S 15mg
Maximum supply semaglutide vial — for sustained protocols at full therapeutic doses
GLP-2 T 15mg
Dual GLP-1 + GIP agonist — superior fat loss and metabolic improvement beyond semaglutide alone
GLP-2 T 30mg
Extended tirzepatide supply for sustained dual-agonist fat loss protocols
GLP-2 T 60mg
Maximum supply tirzepatide — for long-term dual-agonist protocols and best-in-class value
GLP-3 R 10mg
Triple GLP-1 + GIP + glucagon agonist — the most potent fat loss peptide in clinical development
GLP-3 R 15mg
Extended supply triple agonist — for sustained retatrutide protocols at therapeutic doses
GLP-3 R 30mg
Maximum retatrutide supply — best value for committed triple-agonist long-term protocols
GLP-1 C + GLP-1 S
Novel amylin + GLP-1 dual mechanism — exceeds both compounds alone for fat loss and satiety
GLP-3 R 60mg
Maximum retatrutide supply — for aggressive long-term triple-agonist fat loss at the highest dose
Related Protocols
Semaglutide 5mg
The entry-level GLP-1 — 20 weeks of starter supply.
Tirzepatide 15mg
22.5% weight loss — the dual agonist upgrade over semaglutide.
Beginner Fat Loss Protocol
The complete starter stack with titration guide.
Advanced Body Recomp Stack
Tirzepatide + CJC-1295/Ipa for simultaneous fat loss and muscle.