Exactly. Look at the Circassians, a people who trained to withstand the worst of times in order to take advantage of any opportunity. They were famous for their beauty and leanness, and their soldiers were known for eating very little. Their women and men voluntarily entered slavery as purchased wives and warriors because they knew they could control their appetites and behavior better than their fellow slaves and even those who purchased them, which allowed them to strategize and act when others were wailing and wallowing. It's easier to survive when you don't need much, and that permits more energy for making use of available resources.