Peter Attia prefers training on an empty stomach due to personal experience with irritable bowel syndrome.

“for me as somebody that has struggled with like irritable bow syndrome for you know the last 10 years of life I can't think of anything worse than trying to train with anything in my stomach I might have a couple of coffees in the morning um but I'm keeping you know pretty low gut irritant type foods because the minute I feel some kind of you know distension or you know pain in my stomach I cannot train I would rather train hungry with a rumbling stomach than try to have to execute with a full stomach”