Your body can burn calories faster than you can absorb them. And if you’re concerned about what sports medicine says the limits of human absorption are, you’re either a nerd or engaging in extremely intense exercise.
The Tour de France did 124miles on its first day this year. Through mountains.
Many amateur cyclists have a 100 mile single day even or 150-300 mile multi day event as their yearly goal. And they can’t push the sort of power for the duration that a pro can. Something less than 75% as much power for less than half as long per day. And for days instead of weeks.
Sustained cycling is intense exercise. Your body burns through its glucose reserves rapidly, and if you run out of energy the effect ("bonking") is awful. On the other hand, trying to eat a bunch of energy and having too much in your stomach will make you sick and is also awful. So you do in fact want to ingest the most you can process (but no more) per hour, particularly for extended events.
Nutrition doesn't matter for rides up to 15 miles, and you can improvise almost anything for rides up to 40 miles. More (or particularly hilly courses, etc.) and it becomes very important to get the amount you eat and drink right.
I was referring to how Gatorade is a popular beverage for people not doing any kind of intense exercise, not realizing it's just as bad or worse than soda for weight gain in that case.
