Atrial natriuretic peptide is released by the atria of the heart in response to increased blood volume. ANP promotes natriuresis, which is elevated urinary excretion of sodium and chloride, which decreases blood volume. GH inhibiting this explains the extracellular water retention. It does seem as though changing the injection site would help with site-specific responses, but there will always be this systematic response. As far as any ways to combat this......i would say lower your sodium intake slightly and always drink plenty of water, or either just tough it out.