Apparently, when Achilles was young, his guardian fed him the finest bone marrow!
NB: Feed yourself more bone marrow, which can be available via beef shank, and also — feed it to your kids!
To do:
Do more research about how Achilles ate, as well as how the demigods ate?
I think the reason why it is so interesting to study the demigods is that they are part man, part god.