You take clen with food it won't hit you as hard when it comes to the shakes.
Try taking it on an empty stomach in the morning and then do a workout. The shakes will be so bad, you can stay still without moving and you can actually feel your organs inside you shake LOL
For fat loss effects, it doesn't make a difference when you take it.
I have only used the powder and the gel, and I have never got the results that people rave about. I do lose fat, but not that quick to think it's anything special. Maybe I should try the tabs.