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Caloric restriction (CR) has been shown to extend lifespan of various model organisms, most notably mice, but interestingly also in mouse lemurs (
) and rhesus monkeys (In the University of Wisconsin study but not the NIA study).
There are issues, however, with the translatiability of these findings to humans.
Caloric Restriction Delays Visual Signs Of Aging In Lemurs
The control lemur clearly looks unhealthy, and the CR lemur looks young and healthful. The CR group has 30% less calories than the control. The median lifespan for the control group was 6.4 years, compared to 9.6 years for the CR group. When the last control lemur died at 11.3 years, one third...
looksmax.org
There are issues, however, with the translatiability of these findings to humans.
- In at least most of the studies, the researchers augment the caloric intake without altering micronutrient (mineral and vitamins) intake. Therefore, the concentrations of micronutrients are increased in CR groups. Additionally, this reduces the translatiability of the findings to humans, for if a human were to reduce caloric intake, then micronutrients would be reduced as well.
- When researchers implement CR in rodent models, while the ad libitum freely eats throughout the 24 hour day, the CR rodents, hungry for food, will ravenously consume all of their food for the day within a few hour period. This means that, in addition to CR, these groups are basically also doing OMAD or intermittent fasting. Considering the faster metabolism of mice compared to humans, these 20-22 hour fasting periods are comparative to a human fasting for much longer. Additionally, it has been suggested that in the ad libitum groups, the incessant feeding throughout the day could result in circadian clock disturbances.
- Another factor that makes the studies less comparable to humans is that the diets used for CR are usually highly purified. They are eating chow (soy protein, fish meal, constarch, sucrose, soybean oil, micronutrients). It is possible that if one was to eat a whole foods diet, restricting food intake would confer a lesser extension of lifespan than if one were on a purified diet.
- Lastly, not all researchers have prevented obesity in control groups. Some researchers restrict the ad libitum group to 90 or 95% of true as libitum to prevent the obvious detrimental effects of obesity on lifespan and ageing, but many studies fail to prevent obesity in the an libitum control groups. In the longevity community, CR is usually considered an anti ageing strategy regardless of your body fat percentage. However, much of the benefits seem in some experiments could be a result of removeing the harm of obesity in the lab animals.