Notes From the Road, from Kim Zussman
Animal studies suggest all creatures attempt to maximize calorie density, and recall that:
Carbohydrate=4cal/g
Protein=4cal/g
Fat=9cal/g
Since we cannot predict the future, there is survival advantage to consuming as much as currently available and store the excess as fat for leaner times to come.
Rather distinct from devolved creatures with >100%LTV on the lair, and their evolved predators who thought they snuck away with the fat.