Calorie restriction diets have long been thought of as a “fountain of youth” of sorts. Researchers have claimed these diets can help slow the aging process in certain animals, but the effects of such a regimen on human patients have been debated for years. And while there still isn’t any conclusive evidence as to whether such diets can extend human life expectancy or slow aging, a new study suggests that there’s a good chance humans may be able to benefit as well.
According to Business Insider, scientists had previously found that fruit flies, mice, and certain species of worms could take advantage of calorie restriction diets and enjoy longer lifespans. In the case of mice, one study had researchers reducing their calorie consumption by 30 percent, and it was revealed that the diets could improve brain health and extend life expectancy significantly in the rodents. In some cases, the mice’s lifespans had doubled or tripled, the report added.
However, it goes without saying that the same diets that have tremendously positive effects on smaller animals may not have the same effects on larger ones, and may not work as well on people. In fact, scientific research on calorie restriction diets suggests that their impact on monkeys is mixed, depending on the study. Business Insider wrote that “at least one” University of Wisconsin study showed that these diets had positive effects on monkeys, while a National Institute of Aging paper had conversely stated that monkeys on restricted diets had similar life expectancies to those that weren’t on the diets, though they appeared healthier.
— New Scientist (@newscientist) January 18, 2017
Taking the conflicting results into account, UW and NIA scientists had teamed up for a new study, which was published this week in the journal Nature Communications. Data from the rhesus macaques analyzed in the earlier UW and NIA studies was taken and analyzed, and it was found that the studies weren’t that conflicting after all once specific differences were taken out of the equation. Calorie restriction diets, the new study hypothesized, are capable of making monkeys live longer and healthier lives, but such regimes can only work depending on variables such as sex, age at the time they go on the diet, and the actual foods included in the diet.
Originally, the monkeys in the first NIA study had their calorie consumption restricted in their youth, given how this process worked in experiments with mice. The new study revealed that this played a big role in the efficacy, or lack thereof, of calorie restriction – young monkeys do not enjoy any tangible health benefits on restricted diets, unlike the young mice in earlier research. Instead, the diets only extend life expectancy if they are given to adult monkeys.
All in all, New Scientist writes that the rhesus macaques in the study lived three years longer on the special diets, which could translate to nine more years in humans.
One fascinating aside from the study was the observation that male monkeys may put on too much body fat if given the opportunity to eat anything they want. The researchers believe the same may apply to male humans.
The UW and NIA researchers believe that humans and rhesus macaques who, as primates, are more vulnerable to illness as they age, respond in similarly positive ways to calorie restriction diets. Humans, furthermore, are “highly likely” to live longer if on these regimes. But as a separate report from Medical Daily suggested, there’s just too little evidence to suggest that humans can also enjoy longer life expectancies when on calorie restriction.
“My own guess would be that (a calorie restriction diet) is beneficial for some individuals but not for others,” said University of Liverpool lecturer Joao Pedro de Magalhaes in a 2016 interview with Business Insider. “If you don’t have a healthy diet then CR will likely help, but so will other less extreme diets… That said, there are very few studies in humans, so again, this is guesswork.”
[Featured Image by Melissa d’Arabian/AP Images]