From what I understand humans have evolved to run incredibly long distances relatively efficiently because much of our densest caloric intake (historically) came as a result of simply chasing down our prey until it essentially collapsed from exhaustion.
Even though I find that it "feels" more difficult running for my calories (at this distance) I actually end up with surprisingly good performance. I can't help but think there's some fundamental drive and resulting reward system that (subconsciously) thinks "If you don't beat the animal you're chasing you're not eating today".
I imagine something similar happens in terms of your enhanced senses for smell, being similar for foraging (and potentially even prey detection).
This seems to be normal and common when fasting. It happens to me personally and I’ve read comments from other people who experience it too.
- when I am fasting, I believe the hunger itself tweake smell and taste +100 (wonderful)
- if I am fasting, my nose is clearer - this could lead to a more mechanical reason that smell and taste are better
- hot foods accentuate smell and taste. Try biting a sandwich and then take a sip of hot coffee or water - you taste the bite of sandwich more