i only use T-rex before i run in the morning on an empty stomach. 2 caps! i run 16-20 miles a week usually 4 miles a clip. t-rex give me good energy and i break a sweat a lot faster then if i don't take it. for some reason i always have to take a dump after taking t-rex. don't know what is in it. but overall i think its a great way to give you a boost and burn extra calories