Food: Medicine, Drug, or Fuel?

In an excess of the ascetic, the author of The Confessions in Book Ten, Chapter 31 recommends taking food as medicine. At the opposite extreme we find those for whom it is a soporific, a sedative, an escape from reality, a drug. The wise tread the middle path: food is fuel.  

Eat in quantity and quality precisely that alone which optimally fuels fratre asino so that he may bear up well in this vale where his services are indispensable.   Properly fortified, he will carry your load over many a pons asinorum.