Dude, Animal sells SUPPLEMENTS not anabolics! Anything that is legal to buy in your local GMC is, most likely, NOT going to have severe side effects. M-Stak is not a hormone booster, it is a supplement that helps you put on mass by channeling more of what you eat where you want it to go, and not in your midsection. This process is called nutrient partitioning.
Here is the official presentation of the product: http://www.animalpak.com/html/sections.cfm?ID=9
I have used this many times whit grate results and NO side effects.