Calorie restriction

From CRSWiki

Calorie restriction (CR) is the practice of reducing dietary energy intake in order to improve health and slow the aging process. Since the 1930s, extensive scientific research has shown that calorie-restricted diets improve health and extend the lifespan of nearly every species tested, including worms, spiders, rodents, dogs, cows and monkeys. It is the only well-researched, effective means of retarding aging that is available to post-embryonic animals. There is growing evidence that the effects seen in laboratory animals will also be seen in humans.

"Calorie restriction," as it is used by life-extensionists, means a reduction in caloric-intake for the purposes of lowering one's rate of aging as well as preventing disease or the morbidity/mortality associated with disease. For these ends to be achieved, a restriction of energy-intake must not also be accompanied by restrictions of most other essential nutrients, especially vitamins and minerals, at least insofar as such restrictions in essential nutrients would result in sub-optimal intakes of these nutrients.

This is important: CR is not the same as "going on a diet," or simply eating less, or starving oneself.

One often sees other terms in the research literature, terms which connote a slightly different sort of diet, such as "food restriction," "dietary restriction," and so on. These different terms reflect, partly, different conceptions of the mechanism by which "CR" slows aging and prevents disease. In some cases, the terms also reflect different dietary regimens used in experiments. Part of this terminological and methodological confusion results from the difficulty in isolating the effects of a low-calorie diet from the effects of other aspects of the experimental diets. Some of the research that claims to be testing the effects of a calorically reduced, but not otherwise reduced diet has not, in fact, taken sufficient note of the reduction in protein that exists in the diets of the experimental animals, but considers protein only insofar as it contributes energy (calories) to the diet of the animals. Indeed, there are a few researchers who would call other researchers' "CR" experiments "PR" experiments.

The situation is even more complicated than this, given that minimal essential requirements for protein (for humans or rodents), as well as for other nutrients, have yet to be determined precisely.

Nevertheless, there is now widespread agreement that the reduction in energy-intake per se is responsible for most of the positive effects seen in these experiments, even if a few researchers think that the reduction in protein which usually exists in these experiments plays some role also.

The best terms to describe this sort of diet should perhaps be more general, like the "anti-aging diet," or "high/low diet" (high in "good" nutrients, low in "bad" ones), or "undernutrition without malnutrition" -- terms that Roy Walford often uses in his writings (see below for bibliographical info on some of his work). These terms capture the essence of the dietary anti-aging strategy, w/o presuming to have solved the technical questions about the absolutely optimal nature of an anti-aging diet, or the precise mechanisms by which the researched diets exert their effects.

Nonetheless, "calorie restriction," or just "CR," is in widespread use and captures the essence of the diet well. This is the term that this article will use.

Practice

For many people, CR can be challenging to practice, both in terms of "will power" and the technical requirements of maintaining optimal nutrition despite reduced food intake.

Hunger

• The mechanisms of hunger run deeply throughout the brain and body, and as such the effects of calorie restriction can have strong and even suprising effects on our thoughts and behavior.

Binging

• Self-compassion is key
• One method of maintaining constant calories even in the context of occasional binging, is to notice binging events, then fast starting immediatly afterward, skipping the appropriate number of meals until calories are back on track. One problem with this method is that binge eating is typically unplanned, and thus may not be nutritionally balanced or complete.

Nutritional Needs

Get enough vitamins and other (non-caloric) essential nutrients.

Will CR Work in Humans?

(See main article, Will CR Work in Humans?)

We have no definitive answer yet, but most scientists now believe that CR is very likely to slow aging in humans appreciably.

External Links

FAQ by Brian M. Delaney from 2000. Brian M. Delaney has declared that all information from this FAQ may be freely copied to the CR Longevity Wiki. Note, some of the research cited in this FAQ is slightly out of date.

Calorie restriction. Wikipedia article on CR. Note: many CR practioners have questioned the accuracy of this article.