How Does Junk Food 'Slow You Down?'

I’ve heard the statement that consuming unhealthy, processed foods has a detrimental affect to an athlete’s performance, especially speed. The statement seems to be logical, but I’m not sure why this is so other than fat gain. Seeing as many people can consume shitty food and stay lean, would junk food still have adverse affects on the athletes performance, or are there other physiological effects at work other than fat gain?

it fills your leg with bacon

I’m no nutritionist, but… A lot of processed foods are lacking the nutrients and fiber that whole foods have, so there’s less to build/maintain the body with. Also, mitochondria also have a lot of nutritional requirements.

In addition to that, most of these foods don’t fill you as much (and are pretty tasty), so you end up eating more calories that don’t go towards improving the body/performance.

Not to mention the long term effects of a high carb diet with a sedentary lifestyle.

“I’m watching these guys, with their cheeseburgers and stuff. And you’re going to compete against me? Even if you’re younger and faster, your fuel won’t let you beat me.” - Ray Lewis

Apparently he threw away teammate’s bag of chips at locker room , gotta be on something