I only found clen to be effective for "me" if my body % was already low, diet was clean and cardio was on track.... I really didnt like teh sides of slight headache and shakes (being I'm a nurse and it didnt look very professional). Although others like it and find it effective. I prefer ECA as it gives me more energy and am currently using Lipo 6. I've heard Ripped Fuel is good.