IGF-1 DES and IGF-1 LR3 are the two modified forms of insulin-like growth factor 1 circulated in bodybuilding. Both are engineered to escape the binding proteins that normally restrain IGF-1, but they do it in opposite ways — one by removing part of the molecule, the other by adding to it — which gives them different potency-versus-duration trade-offs.
At a glance
| IGF-1 DES | IGF-1 LR3 | |
|---|---|---|
| Full name | DES(1-3)IGF-1 | Long R3 IGF-1 |
| Modification | Missing the first 3 amino acids | Arg substitution + 13-amino-acid extension |
| Binding-protein evasion | Yes (low affinity) | Yes (low affinity) |
| Relative potency | Higher acute potency in tissue | Lower than DES, but still potent |
| Duration of action | Short-acting | Long-acting (much longer half-life) |
| Human evidence | Animal / cell studies only | Animal / cell studies only |
| Status | Research chemical; WADA-banned | Research chemical; WADA-banned |
The bottom line
The real distinction between these two is potency versus duration. IGF-1 DES is reported to be more potent in the short term, while IGF-1 LR3 trades some of that acute potency for a far longer half-life. In bodybuilding folklore these properties are mapped onto different uses, but that framing rests entirely on the compounds' laboratory pharmacology — neither has any controlled human trial for muscle growth or performance. Both are unapproved research chemicals with unknown human safety and are banned in sport.
Frequently asked questions
What is the difference between IGF-1 DES and IGF-1 LR3?
Both are modified IGF-1 forms that evade binding proteins. IGF-1 DES is truncated — missing its first three amino acids — and is more potent acutely but short-acting. IGF-1 LR3 is extended and substituted, making it less potent per molecule but much longer-lasting.
Which is stronger, IGF-1 DES or LR3?
IGF-1 DES is generally described as more potent in the short term, while LR3 has a much longer duration of action. However, these comparisons come from laboratory pharmacology, not from human trials, so real-world differences in people are unknown.
Do IGF-1 DES or LR3 build muscle in humans?
There is no controlled human evidence that either builds muscle or improves performance. Their effects are extrapolated from animal and cell studies. Both are unapproved research chemicals with unknown human safety and are banned in sport by WADA.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Martin AA, Tomas FM, Owens PC, et al. IGF-I and its variant, des-(1-3)IGF-I, enhance growth in rats with reduced renal mass. Am J Physiol. 1991. Peer-reviewed study
- Lemmey AB, Martin AA, Read LC, et al. IGF-I and the truncated analogue des-(1-3)IGF-I enhance growth in rats after gut resection. Am J Physiol. 1991. Peer-reviewed study
- Ballard FJ, Wallace JC, Francis GL, et al. Des(1-3)IGF-I: a truncated form of insulin-like growth factor-I. Int J Biochem Cell Biol. 1996. Peer-reviewed study
- Li M, Li C, Parkhouse WS. Age-related differences in the des IGF-I-mediated activation of Akt-1 and p70 S6K in mouse skeletal muscle. Mech Ageing Dev. 2003. Peer-reviewed study
- Voorhamme D, Yandell CA. LONG R3IGF-I as a more potent alternative to insulin in serum-free culture of HEK293 cells. Mol Biotechnol. 2006. Peer-reviewed study
- Mongongu C, Coudore F, Domergue V, et al. Detection of LongR3-IGF-I and related analogs for antidoping purposes. Drug Test Anal. 2021. Peer-reviewed study
- Renehan AG, Zwahlen M, Minder C, et al. IGF-I, IGFBP-3, and cancer risk: systematic review and meta-regression analysis. Lancet. 2004. Peer-reviewed study
- Lu Z, Liu N, Huang H, et al. Recombinant expression of IGF-1 and LR3 IGF-1 fused with xylanase in Pichia pastoris. Appl Microbiol Biotechnol. 2023. Peer-reviewed study
- Hadsell DL, Parlow AF, Torres D, et al. Enhancement of maternal lactation performance during prolonged lactation in the mouse by mouse GH and long-R3-IGF-I is linked to changes in mammary signaling and gene expression. J Endocrinol. 2008. Peer-reviewed study
- Engel MG, Narayan S, Cui MH, et al. Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice. J Alzheimers Dis. 2025. Peer-reviewed study