[bajsejohannes]

Not really. What you do is create a temporary account for each session, unless one exists already. If the user chooses to create an account later, it is not really created, but the temporary account is promoted to a permanent one, and the details like username are filled in.

Again, check out stackoverflow.com. They do this.

[doctorj]

Unlike stackoverflow.com the food recommendations generated by Usable Health are dependent on each of the answers in the sign up process. For example someone who weighs a 100 pounds will receive different recommendations from someone who weighs 200 pounds so unfortunately there is no way of getting around the complete sign up / nutritional profile creation process.

[bajsejohannes]

I see! Well, then I agree that my suggestion might not be a good fit. (I was fooled by the fact that I could try it without entering any details)