meaty  adjective
Prompting considerable thought: a meaty theme for study and debate.

meat (INTEREST) noun [U]
 important, valuable or interesting ideas or information
 I think there was a lot more intellectual meat in the degree courses in those days, you
 know.

 meaty   adjective
 a meaty book/letter/report
 She has written some wonderfully meaty parts for actresses.

 meatiness   noun [U]