Besides sleeping, how long do you think you could go without eating? Okay, well how long do you think you would want to go without eating?
For most people, we could probably go half a day without a meal before it got too uncomfortable, and we wouldn't want to do it anytime soon again either.
But there's a disturbing new trend where young people are purposely depriving themselves of food in order to gain some sort of benefits for their mental, physical, and spiritual health.
Many high-profile business and technology executives have been recommending fasting to their employees as a form of productivity boosting.
They claim that by deciding not to eat for long periods throughout the day, you will not only gain more willpower but become healthier because, they believe, fasting prevents illnesses from getting worse.
There is even an app that has been developed called Zero, that keeps track of your non-eating habits.
But doctors and nutritionists are not having any of it.