Certainly, I find I don't really need breakfast most days. I feel my best when I wake up, have a coffee (there's some oat milk in there so a few calories), get a swim in, and then have an early-ish lunch. If I eat breakfast I never feel right in the pool.

I have a very similar routine! Though I prefer to swim on an empty stomach and have a coffee after as a reward :)

When you wake up your liver start converting stored glycogen and pumping out glucose so your fasting blood sugar is high enough to function. Your body is actually adapted for morning fasting.

Diabetics have to be aware of this and time their meds appropriately.