I think this site has been designed brilliantly, and written just as well - you rarely see the two together. All the information you could possibly want to know about your product is there, and easily accessible.
The only thing I could say, which I have said time and time again is the block of text shown on the
Clinical Study page. It is daunting to users and can put them off reading it altogether. However, in this case I am willing to make an exception. As I could not think of any images - my usual suggestion for this problem to use. Anyhow, I think it is paragraphed well, making good use of subtitles. You can only have so many images about weight loss tablets. No? :P
Just out of interest, did you design the site yourself, or did you purchase it from a third party?