The best type to take apparently is Humalog, but I went with(and alot of guys do for the same reason) Humulin-R, since it requires no Prescription for its' purchase. If you go with Humulin-R, keep in mind that it has a 1/2-life of 12 hours(as opposed to 4 with Humulog), and you should keep your fat intake to a BARE MINIMUM for that long after you inject. I can put on a pound a day with that shit but when I first started it, I was only watching my fat intake for the first 4 hours, and couldn't figure out why I was putting the old love-handles back on. After cutting my fat intake to about 3 grams(max) for the first 12 hours after an injection, I have seen better results. I threw in some mild cardio(which I never do--I diet) for good measure as well.