What is the best diet supplement for women?

Hi! I'm 23 years old and am trying to lose some weight. I am doing some moderate excercising, as moderate is all I have time for, and am watching what I eat. What is a good diet supplement, pills or for shakes, that is safe to take and works most effectively w/out side effects?

Suggestions would be greatly appreciated,

Thanks :) Calcium? Interesting, thanks.

Any idea where I can get Wu Yi tea?