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Understanding IGF-1. IGF-1 works a little different than Testosterone. In an athlete, one typically sees LOW levels of free IGF-1 and high levels of IGFBP-3. In order to utilize IGF-1, the body needs sufficient amounts of IGFBP's (IGF Binding Proteins). Testosterone is different; it works when it is unbound. Bound Testosterone, either via albumen or SHBG, is useless Testosterone. The levels of these binding proteins are determined genetically. I am unaware of drugs that truly enhance the levels of the IGFBP's. Sure, there are drugs that lower estrogen levels and seem to also lower SHBG and Albumen. The key is high IGFBP-3 levels. Perhaps the key to high IGFBP-3 levels is a low BF%. Any thoughts?
