I found this which is a good overview
And some select snippets which I completely agree with:
So What Does All This Mean?
Phenocal contains so many ingredients it’s unlikely that sufficient quantities exist to have much of an effect. The use of a proprietary blend means it’s impossible to know just how much exists!
So Does Phenocal Work?
In the “science” bit of how Phenocal works attention is focused on only two of the ingredients, “Fucoxanthin” and “Glucomannan”. This somewhat suggests these are the key ingredients that underpin the success of this product.
So basically there are 2 ingredients that may help. Glucomannan is a pretty good fiber supplement. If you care about the ingredients that may help in the pill, they can be bought cheaply at any drug store.