Caloric restriction is reported to slow degeneration in the human body. Is there scientific basis to support these claims? How widely accepted are they?
1 Answer
Calorie restriction is a complex phenomenon as the effects can vary depending on how much you restrict calories to when you restrict them. You can do daily calorie restriction, or you can restrict your calories with fasting in various intermittent fasting protocols.
For the benefits of restricting calories, there seems to be several studies showing benefits in longevity and health. However, the fact that restricting calories will in most cases lead to weight loss, it is hard to determine whether it is the restriction itself that has benefits (and the hormonal changes that occur in the body due to restriction) or simply from the weight loss itself.
This study, which is done on rodents, show that there are changes on the cellular level that can increase the lifespan of rodents: http://www.sciencedirect.com/science/article/pii/S1357272502000389
This study shows that several age-related diseases can decrease with long-term calorie restriction. However, this study discusses the effects it has on yeast, worms, flies and rodents, and links these hypothetically to primates: http://www.nature.com/nrm/journal/v6/n4/abs/nrm1616.html
This is a similar study as the one above. It discusses studies done on yeast, worms, flies, rodents, and some primates (the Rhesus monkey) and draws conclusions from those studies to humans: http://www.sciencedirect.com/science/article/pii/S0047637405000874
This study is similar to the one above: http://www.sciencedirect.com/science/article/pii/S0092867405001030
I find the conclusion of the last study to be of interest:
CR has long been recognized for its ability to extend mammalian life span and to mitigate disease processes in many tissues. Humans have not fully harvested the benefits from the regimen, in part because of the extreme difficulty in complying with the regimen.
Long term calorie restriction is very difficult for humans, and since we cannot do lab studies on humans, it is very hard to determine the long term effects of CR. However, there are several studies that seem to indicate that intermittent fasting (IF) can produce similar results as CR, and that IF can be much easier for humans to maintain in the long term. Since IF is not the topic of this question I will not link to studies.
