IGF-1 LR3 vs HGH 191AA
Two anabolic research compounds sitting at different points on the same axis — one is growth hormone itself, the other is the extended-acting downstream signal it produces. This comparison covers mechanisms and which fits which anabolic research question.
IGF-1 LR3
Extended-bioavailability IGF-1 analogue. Reduced IGFBP binding extends half-life from minutes to ~20-30 hours for direct receptor activation.
Shop IGF-1 LR3 →HGH 191AA
191-amino-acid recombinant human growth hormone, identical to endogenous GH. Directly raises GH levels regardless of pituitary status.
Shop HGH 191AA →Side-by-Side Comparison
| Factor | IGF-1 LR3 | HGH 191AA |
|---|---|---|
| Axis position | Downstream (IGF-1 receptor) | Upstream (pituitary GH replacement) |
| Half-life | ~20-30 hours (LR3 modification) | Short — dosed by IU, daily protocols |
| Mechanism | Direct IGF-1 receptor activation | Direct GH replacement, stimulates hepatic IGF-1 |
| Molecular weight | 9,117.5 Da | 22,124 Da (191 amino acids) |
| Dosing unit | mg (mcg-scale, 0.1mg vial) | IU (International Units) |
| Feedback preservation | Bypasses natural GH feedback loop | Also bypasses pituitary feedback (unlike secretagogues) |
| Best for | Direct, sustained IGF-1 receptor research | Direct GH-deficiency replacement and lipolysis research |
Mechanism Deep Dive
IGF-1 LR3 — Extended Downstream Signal
IGF-1 LR3 carries a 13-amino-acid N-terminal extension and a glutamic acid substitution that dramatically reduces IGF-binding-protein (IGFBP) binding. This keeps it bioavailable in circulation far longer than native IGF-1, sustaining protein synthesis, glucose uptake, and satellite cell activation research through direct IGF-1 receptor signalling.
Shop IGF-1 LR3 →HGH 191AA — Direct GH Replacement
HGH 191AA is sequence-identical to endogenous pituitary GH. Rather than stimulating the pituitary (as secretagogues do) or acting downstream (as IGF-1 LR3 does), it directly replaces or augments circulating GH — driving lipolysis, IGF-1 elevation, and tissue repair research independent of the body's own GH secretion status.
Shop HGH 191AA →Which Peptide Wins For Each Goal?
Direct IGF-1 receptor / anabolic signalling research
IGF-1 LR3
Acts directly on the downstream receptor without depending on hepatic conversion or pituitary status.
GH-deficiency replacement research
HGH 191AA
Sequence-identical exogenous GH, directly replacing what the pituitary would otherwise secrete.
Lipolysis / body composition research
HGH 191AA
Supraphysiologic GH dosing has well-documented lipolytic effects independent of IGF-1 pathway activation.
Isolating GH-axis vs IGF-1-receptor effects
Both together
Comparing upstream GH administration against direct downstream IGF-1 LR3 activation helps separate the two stages of the axis.
Frequently Asked Questions
What is the difference between IGF-1 LR3 and HGH 191AA?
HGH 191AA is recombinant human growth hormone itself — it acts upstream, raising GH levels which in turn stimulate the liver to produce IGF-1. IGF-1 LR3 is a modified, long-acting analogue of the downstream IGF-1 molecule, acting directly on IGF-1 receptors without needing to pass through the GH-to-liver conversion step.
Which raises IGF-1 more directly: IGF-1 LR3 or HGH 191AA?
IGF-1 LR3 raises tissue-level IGF-1 receptor activity directly and immediately since it is itself an IGF-1 analogue. HGH 191AA raises IGF-1 indirectly by stimulating hepatic IGF-1 production, which takes longer and depends on liver responsiveness.
Can IGF-1 LR3 and HGH 191AA be researched together?
Yes — because HGH raises systemic GH and stimulates broad IGF-1 production while IGF-1 LR3 provides sustained, localized IGF-1 receptor activation, they are sometimes studied together to separate upstream GH-axis effects from direct downstream IGF-1 receptor effects.
Research use only. All products sold by JA Performance are strictly for laboratory and in vitro research purposes. Not for human consumption, medical use, or veterinary use.