Is evolutionary fitness equivalent to energy eficiency?

Answer 1

No. I'm not energy efficient. I eat a lot of food, consume a lot of fuel to keep warm, etc. Yet, we're at the top of the evolutionary food chain.

Reptiles,being cold blooded require less food.

When humans consume all of the food and fuel what will become of our world?

Maybe that is what is meant by "the meek shall inherit the earth".

Answer 2

Evolved animals make better use of available resources than their predecessors thus in a way yes.