What is IGF-1 LR3?
IGF-1 LR3, Long-Arg3-IGF-I, is an Insulin-like Growth Factor 1 (IGF-1), synthetically created. It’s shaped somewhat like IGF-1 but is much less active for IGF-binding proteins than native IGFs-I and -II. This implies that it binds less to these proteins and can influence its biological activity [1].
But to be clear, while IGF-1 LR3 is similar to IGF-1, it is not the same, so it could act differently in the body. As such, it needs to be handled with care and under supervision.
Benefits of IGF-1 LR3 for Muscle Building
It’s possible that IGF-1 LR3 can activate muscle growth and reverse muscle degeneration. It enacts the IGF1R/IRS1/PI3K/Akt cascade leading to skeletal muscle hypertrophy [2]. A study showed that IGF-1 LR3 phosphorylated AKT1, an IGF-1 signalling mechanism, promotes the differentiation of muscles [3].
IGF-1 LR3 could even repair muscles. It increases MSC proliferative potential for muscle repair and regeneration [3]. IGF-1 LR3 may also block muscle proteolysis (shrinkage), which preserves muscle protein and weight [4].
Risks of IGF-1 LR3 for Muscle Building
Even IGF-1 LR3 comes with risks. IGF-1 makes cells grow and divide, allowing for cancer-causing cell proliferation.
Another risk is hypoglycemia or low blood sugar. IGF-1 is insulin-like and will make the blood sugar drop; if uncontrolled, it might cause hypoglycemia [4].
Lastly, while IGF-1 LR3 can promote muscle growth this may not necessarily increase strength. In fact, one study found that muscle mass rose, but muscle strength declined in parallel [6].
What evidence is there for IGF-1 LR3 for fat loss?
Insulin-like growth factor-I (IGF-I) does have anabolic or protein-building properties that can impact weight and physique. Yet the real-life alias of IGF-I (LR(3) IGF-I) doesn’t directly play a role in fat loss. In one study on rats, LR(3)IGF-I was infused at different rat food intake rates. The experiments revealed no preservation of muscle protein but that the rats with LR(3)IGF-I remained fatter and nitrogen-retentive. As it turns out, LR(3)IGF-I infusion resulted in fat loss only in young rats, although plasma insulin declined in both age groups [1].
A separate study revealed that metformin in cancer survivors who were obese reduced their IGF-1 levels to the point of weight loss. However, the effect seemed to diminish over time [7].
What are the possible side effects of taking IGF-1 LR3?
We may not have enough data to understand exactly the dangers of IGF-1 LR3, as few studies mention IGF-1 LR3. However, some studies do discuss the related risks with fluctuations in IGF1 and its binding proteins.
IGF1 is anabolic and growth-stimulating, so there’s a potential risk that it can induce tumour growth [8]. For example, more of a binding protein called IGFBP3 was related to a higher risk of colorectal cancer in older men [8]. Similarly, specific polymorphisms in the IGF1 gene were associated with an increased risk of childhood acute lymphoblastic leukaemia [9].
In the case of metabolic diseases, elevated levels IGFBP-3 could increase risk of T2DM independently of IGF-1 [10]. IGF1 levels that were low or high were also predictive of diabetes [11].
To measure cardiovascular health, increased IGFBP1 and decreased IGFBP3 predicted mortality of general and cardiovascular diseases in elderly men [11].
These risks involve changes in the levels of IGF1 and its binding proteins, not necessarily IGF-1 LR3. More work must be done to learn more about the precise dangers of IGF-1 LR3.
Conclusion
IGF-1 and its derivatives alter body weight and physiology, but the evidence for fat loss or muscle building with IGF-1 LR3 is not robust. This is still unclear and will require more studies to grasp what IGF-1 LR3 can and cannot do in this scenario.
Importantly, if you take these supplements, do your due diligence on the risks and talk to a certified medical professional about them because they’re not well-researched, and the side effects are well known. Furthermore, some peptides are not sold in certain countries.