Hereinafter are a couple of other scientific based data to support the unique synergistic effect of GH and IGF1
http://www.ncbi.nlm.nih.gov/pubmed/9129466
------------conclusions -
GH and IGF-I combined further enhanced fat oxidation while reducing protein catabolism. Serum insulin concentrations were significantly increased by GH but decreased by IGF-I. GH significantly decreased serum total triiodothyronine concentrations and IGF-I significantly decreased serum corticosterone concentrations.
http://www.ncbi.nlm.nih.gov/pubmed/10571453
-----------results and conclusions
RESULTS:
Administration of IGF-I, but not GH, attenuates dexamethasone-induced protein catabolism and increases insulin sensitivity. Simultaneous treatment with GH and IGF-I additively increases the serum concentration of IGF-I, whole-body anabolism, and lipid oxidation. GH or IGF-I when given alone produces similar increases in the serum concentration of IGF-I. However, GH selectively increases skeletal muscle mass whereas IGF-I selectively attenuates the intestinal atrophy and abnormal intestinal ion transport induced by TPN. These tissue-selective anabolic effects of GH and IGF-I are associated with differential increases in protein synthesis in skeletal muscle and jejunum, respectively.
CONCLUSIONS:
Simultaneous treatment with GH and IGF-I may offer the greatest clinical efficacy because of improved nitrogen retention in association with enhanced lipid oxidation and stimulation of protein synthesis in multiple tissue types.