What is IGF-1 LR3?
IGF-1 LR3, also known as Long-Arg3-IGF-I, is a synthetic analog of Insulin-like Growth Factor 1 (IGF-1). It has a similar structure to IGF-1 but with a much lower affinity for IGF-binding proteins compared to native IGFs-I and -II. This means that it binds less readily to these proteins, which can influence its biological activity [1].
However, it's important to note that while IGF-1 LR3 shares similarities with IGF-1, it is not identical and may have different effects in the body. As such, it should be used with caution and under appropriate supervision.
Benefits of IGF-1 LR3 for Muscle Building
IGF-1 LR3 may be able to stimulate muscle growth and prevent muscle wasting. It activates the IGF1R/IRS1/PI3K/Akt pathway, which induces skeletal muscle hypertrophy [2]. A study showed that IGF-1 LR3 increased the phosphorylation of AKT1, a key effector of IGF-1 signalling, promoting muscle differentiation [3].
IGF-1 LR3 also has the potential to enhance muscle repair. It increases the proliferative capacity of MSCs, which are crucial for muscle repair and regeneration [3]. Moreover, IGF-1 LR3 can potentially inhibit muscle proteolysis (breakdown), thus preserving muscle protein content and mass [4].
Risks of IGF-1 LR3 for Muscle Building
Despite its potential benefits, IGF-1 LR3 also carries risks. High concentrations of IGF-1 are associated with an increased risk of cancer and mortality [5]. This is because IGF-1 promotes cell growth and division, which can lead to uncontrolled cell proliferation, a hallmark of cancer.
Another risk is hypoglycemia or low blood sugar. IGF-1 has insulin-like effects, which can lower blood sugar levels, potentially leading to hypoglycemia if not properly managed [4].
Lastly, while IGF-1 LR3 can promote muscle growth, it may not necessarily lead to increased strength. One study found that while muscle mass increased, muscle strength did not improve correspondingly [6].
What evidence is there for IGF-1 LR3 for fat loss?
Insulin-like growth factor-I (IGF-I) is known to have anabolic or protein building effects, which can influence body weight and composition. However, the specific analogue of IGF-I, known as LR(3) IGF-I, does not appear to directly contribute to fat loss. In a study conducted on rats, LR(3)IGF-I was infused at varying levels of food intake. The results showed that while the rats infused with LR(3)IGF-I maintained higher body weight and nitrogen retention, muscle protein was not conserved. Interestingly, LR(3)IGF-I infusion increased fat loss only in young rats, despite a reduction in plasma insulin levels in both age groups [1].
In another study, it was found that metformin treatment in cancer survivors with obesity led to significant decreases in IGF-1 levels, which was associated with weight loss. However, this effect seemed to wane over time [7].
What are the possible side effects of taking IGF-1 LR3?
There may not be sufficient evidence to answer exactly about the risks of IGF-1 LR3 as there are few studies specifically mentioning IGF-1 LR3. However, they do provide information about the general risks associated with alterations in levels of Insulin-like Growth Factor 1 (IGF1) and its binding proteins.
IGF1 has anabolic and growth-promoting effects, which raises concerns about its potential to promote tumor growth [8]. For instance, higher levels of a binding protein called IGFBP3 were associated with an increased incidence of colorectal cancer in older men [8]. Similarly, certain polymorphisms in the IGF1 gene were associated with an increased risk of childhood acute lymphoblastic leukemia [9].
In terms of metabolic diseases, higher levels of IGFBP-3 might raise the risk of type 2 diabetes mellitus (T2DM) independent of IGF-1 levels [10]. Both low and high IGF1 levels were associated with an increased risk of developing diabetes [11].
In terms of cardiovascular health, higher IGFBP1 and lower IGFBP3 levels were found to predict overall and cardiovascular disease-related mortality in older men [11].
It's important to note that these risks are associated with alterations in the levels of IGF1 and its binding proteins, not specifically IGF-1 LR3. More research is needed to understand the specific risks associated with IGF-1 LR3.
Conclusion
While IGF-1 and its analogues can influence body weight and composition, the evidence does not strongly support the use of IGF-1 LR3 specifically for fat loss or muscle building. More research is needed to fully understand the potential benefits and limitations of IGF-1 LR3 in this context.
Crucially if you are thinking of taking these supplements, please consider the risks carefully as discuss with a licensed medical practitioner as they are often under-researched and the side effects ill understood. Additionally, some peptides are illegal to purchase in certain countries.
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