I've done it for both, I used it for the last four weeks of a bulker. Using it now as a bridge with a 4-4-4 insulin pattern, designed by LA (4weeks slin-four weeks-igf-4weeks slin. Keep in mind that if you use it near insulin, it will make you much more insulin receptive, it caused me to go slightly hypo. I like it during the tail end of a bulker, it'll make you shed some bodyfat, and kick your hunger up 10 fold.