I am German but have lived in the US for more than 25 years. Sometimes I discuss with my German friends what I am doing here as a trainer, and they are usually surprised that I do well. The general opinion seems to be that me ex-fellow countrymen are not into coaching or training the way we are in the US.
I have a few comments about your website, though. All it seems to do is make a case why people should be buying the book which will tell them how to lose belly fat. I did not see anything from you other than that you recommend it. I also felt that it could be improved from a language standpoint. To talk from the heart is fine, but it loses its point when it is written.
If you want to market yourself as a coach, you need to establish at least an outline as to what people will have which they cannot get by reading the book.
You live in a major city with several large sports clubs. Have you considered offering free lectures on the subject? They may let you do that as long as it does not cost them anything. Then you can hand out information and business cards.