Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Calorie restriction (CR) is a diet proven to improve wellbeing and maximum life span in rodents and primates, restricting calorie intake to a level 20-40% lower than is typical, while still obtaining all the necessary vitamins, minerals and other important nutrients. Though CR diet is described to be a longevity diet , a new US study carried out on monkeys showed that those whose calories were restricted to 30% below normal did not live longer. Learn more about calorie restriction diet and its effectiveness, by reading this book.