Not a problem at all. You lose some peak performance but barely any endurance on short fasts. When I was getting ready for the prom I was working out, swimming

Not a problem at all. You lose some peak performance but barely any endurance on short fasts. When I was getting ready for the prom I was working out, swimming and fasting for two weeks (only protein 200-400 calories). It was uncomfortable but totally manageable. Warriors have waged whole wars depraved of adequate nutrition.