Use it for at least 8 weeks. I used it last year with the fat loss stack and lost around 25lbs. Im using it again and even more serious about my diet and the fat is just melting off. The timing between both dermatherm and dermacrine will be tricky, as you have to apply one let it dry, absorb. It takes something like 6 hours for it to evaporate entirely, so I would choose one or the other.