Introduction: Characteristics of Fasting
Total Fasting and Dietary Restrictions Fasting is dened as a voluntary or involuntary abstention from food, accompanied or not by water consumption. From a medical point of view, the fasting period starts from the sixth hour after the last meal. Fasting has been known since antiquity, and it has been practised for both medical and spiritual reasons. In the classical era, good health was thought to depend upon an appropriate balance of four body humors, and dieting, along with purging and leeching, was a frequent element in the physician’s advice. Thus Hippocrates said :
And Plutarch advised :
In our modern society, various forms of dietary restriction are frequently encountered. Physicians classify their patients in terms of their body mass index (BMI; the
ratio M/H2, where M is the body mass in kg and H is the standing height in meters). A large proportion of sedentary individuals are overweight (BMI > 25 kg/m2) or obese (BMI > 30 kg/m2). Those who are overweight or obese are at an increased risk of various chronic diseases, and physicians will attempt to restore an optimal BMI (20-25 kg/m2) by a combination of increased physical activity and a decreased food intake sufcient to create a negative energy balance of 2-4 MJ/day. Physicians also impose short periods of fasting as a prelude to anesthesia.