"The Chinese noted with surprise and disgust the ability of the Mongol warriors to survive on little food and water for long periods; according to one, the entire army could camp without a single puff of smoke since they needed no fires to cook. Compared to the Jurched soldiers, the Mongols were much healthier and stronger."
Genghis Khan had it figured out 800 years ago: "The Chinese noted with surprise and disgust the ability of the Mongol warriors to survive on little food and water for long periods; according to one, the entire army could camp without a single puff of smoke since they needed no fires to cook. Compared to the Jurched soldiers, the Mongols were much healthier and stronger."