IGF-1 LR3

Both are engineered IGF-1 variants that bind IGF-binding proteins far less than native IGF-1 does. IGF-1 DES is native IGF-1 missing its first three amino acids; LR3 swaps one amino acid and adds a 13-amino-acid extension. In cultured rat muscle cells the two were about equally potent, and both beat IGF-1 (Francis, 1992). In a pig study, DES lowered blood glucose the most of the variants tested (Tomas, 1997). Vendor and forum copy describes LR3 as long-acting, with a 20-30 hour half-life, and DES as short-acting and injected into a muscle right before training. The half-life figure has no measured source: in rats, LR3 left the blood faster than native IGF-1. Neither variant has been studied in people.

IGF-1 is structurally similar to insulin and can act through the insulin receptor, though more weakly than insulin. In pigs, LR3 lowered blood glucose 2-3 times more than the same dose of IGF-1 and kept it down longer, with 4-8 times more total glucose lowering over 4 hours (Tomas, 1997). There are no human data. Hypoglycemia (shakiness, sweating, tunnel vision) is the risk users report most, and many describe eating carbohydrates around each injection; that's community practice, not a tested protocol. Severe low blood sugar is a medical emergency, so talk to a healthcare professional before using any compound that lowers blood glucose.

We found no study of LR3 that measured fat loss. Vendor copy says it promotes lipolysis (fat breakdown) and steers nutrients toward muscle instead of fat, but no LR3 data support either claim; the 1990s rat studies focused on body weight, organ weights and nitrogen retention. Semaglutide is an FDA-approved prescription medicine for weight management, tested in large trials, and tesamorelin is approved only for excess abdominal fat in HIV-associated lipodystrophy. Research-use versions of either aren't equivalent to the prescription products.

No study has compared the two routes for LR3, and none has tested injecting into a muscle just trained. Users describe both. Some prefer intramuscular injection into the trained muscle on the theory that it boosts local effects, while others report subcutaneous injection for body-wide effects. In the rat studies the peptide was given under the skin, and continuous infusion by pump worked better than once- or twice-daily injections (Tomas, 1996).

No study has tested cycle length for LR3. Vendor guides commonly list 4-6 weeks followed by an equally long break, and forum users describe cycles of 4-8 weeks. The usual reason given is receptor downregulation, which hasn't been measured for this analogue. Whether longer use raises side-effect risk is unknown, because there are no human data at any duration.