Nobody said you had to eat right before a cardio workout
if you aim like 60-90 minutes prior and focus on proper nutrition and getting some carbs around HIIT you should be fine.
Do you think swimmers go into a meet with no fuel in the tank? i highly doubt it
Endurnace runners going to go run a marathon on an empty? I highly doubt it.
Set yourself up for optimal performance.
What is optimal? And is comparing an elite level performer to someone looking to lose fat a fair comparison? During a meet or race, the idea is to win - not lose weight. Performance is necessary if performance is what you're seeking.
If I run on a treadmill, I dont weigh myself and then replenish water after a race. I dont eat gel packs midway through. I dont urinate in the cup holder to save time. I just run. It doesnt need to be 'optimal' for that.
An athlete also dedicates his/ her life to the sport - in many cases their practices are impractical or damn near impossible for the average joe with a job and life outside of the gym.
I always have leucine in hand and dump a small amount into a inch of water and shot it back with each meal. Nothing extreme, nothing fancy, just easy and convenient.