I tried the Eat-Right-4-Your-Type diet and it was very bad.
I think that only experimentation can tell what is good for
you or not.

One theory I have not tried is the Instincto (sic?)
from france(?) where you smell food before eating it.
If it smells good then eat it.  This depends on your
sense of smell to tell you what food is good for you
right now.  The same food may not be good for you tomorrow.
When you make a meal you make up lots of
raw foods and then snif them before eating.  It may be
that what your body needs today is just one bite of
something, then it does not smell good after the first bite.

R. Keene