It is not the first time that scientists have linked caloric restriction with a slowdown in aging and even with cancer (disease, in fact, directly associated with this inexorable process of the passage of time). But now, a new study provides the strongest conclusions yet regarding how reducing calories in the diet could help slow human metabolism, thereby increasing life expectancy.
The study results are so conclusive that they reinforce the hypothesis that a low-calorie lifestyle, or treatments that mimic the biological effects of restriction, could prolong life.
So far, similar studies have been done with animals with a short life cycle, such as worms, flies and mice. The current experiment, carried out in humans, is pioneering, since studies of these characteristics in animals with longer lives, such as primates, are more difficult to carry out.
Specifically, the trial looked at the effects of 2 years of caloric restriction on metabolism in more than 200 healthy, non-obese adults between the ages of 21 and 50.
34 people in one group reduced their calorie intake by an average of 15%, and 19 people in another control group ate as usual.
At the end of two years, the diet participants were found to be using energy much more efficiently than the control group . This reduction in their metabolic rate was greater than the test group’s weight loss, which was nearly 9 kilograms per participant, on average.
All other clinical measures were reduced, reaching rates of decrease in damage due to aging.
The Biochemistry of Longevity
In the 1990s, scientists began to identify the genes and biochemical pathways involved in longevity in certain animal models, including the fly Drosophila melanogaster . These included pathways of insulin sensitivity and the function of mitochondria (tiny structures in cells that use oxygen for energy).
Later studies revealed that calorie restriction activated similar pathways in mice and monkeys. Mice on restricted diets can live up to 65% longer than mice that are allowed to eat freely, and the results in primates, although more difficult to make, yielded similar results.
Against this background, the lead author of the new study wanted it to be “the Rolls-Royce” of human longevity studies, physiologist Leanne Redman.
However, it is unknown whether the conditions of the study could be implemented since, according to the researchers, the caloric restrictions of the participants were very severe. “Few people could restrict their diet so severely,” they acknowledge. “But understanding the biology involved in calorie restriction and how this can slow aging will be very helpful.”
The next step will be to repeat the study, with a less ambitious caloric restriction, in a balanced diet, and that also contains antioxidant foods (to control oxidative stress), or with chemicals such as resveratrol , which mimics the aspects key to calorie restriction in the diet.
The study was prepared by the Pennington Center for Biomedical Research, within the framework of a large-scale study called CALERIE (Comprehensive Assessment of Long-Term Effects of Reducing Energy Intake), sponsored by the National Institutes of Health of the United States.
