If a male cyclist eats a super high-fat diet for 6 days and then loads up on carbs for 1 day, it won’t slow them down in a 100-km race compared to eating lots of carbs all along.

If elite male cyclists eat a super high-fat diet for 6 days before carb-loading for a day, they’ll feel just as fast over a long 100-km ride — but they’ll have less power for short, intense sprints compared to when they eat a high-carb diet first.

If elite male cyclists eat a super high-fat diet for six days and then carb-load for one day, they’ll perform worse in sprints—even though they don’t feel more tired, their heart rate doesn’t change, and their muscles fire the same way.

If male cyclists eat a super high-fat diet for six days, their body's 'fight or flight' system might get a bit more active — and that change doesn’t go away right after they start eating carbs again.

Whether you eat carbs, protein, or nothing before a hard cycling workout with short bursts of maximum effort, your power output stays the same — your body can still push hard regardless of what you ate beforehand.

For endurance athletes, switching to a high-fat diet for six days and then loading up on carbs doesn’t seem to boost performance in a one-hour cycling test compared to sticking with a high-carb diet.