Is excessive calorie consumption the only reason we live shorter lives? The relationship between caloric intake and longevity is somewhat more complex, and factors such as genetics come into play. This is what a study published by the scientific journal Nature demonstrates, in which almost a thousand genetically diverse mice were analyzed.
The research, led by the Jackson Laboratory in the United States and available in the National Library of Medicine in that country, indicates that, although calorie restriction extended life in all rodents, the effects on their health were different. These data also provide clarity on the criteria for measure life expectancy and health expectancy, two different concepts and both related to aging.
Calorie restriction to live longer?
The study subjected 960 female mice, representing a wide range of physiological characteristics, to five different interventions: one group would have a normal diet, unlimited food consumption; another group would see their caloric intake reduced by 20 percent; while a third group would eat up to 40 percent fewer calories.
Two other groups were put on an intermittent fasting diet, that is, one group fasted one day a week, while another fasted two consecutive days a week.
Additionally, the authors, led by Alison Luciano, collected and cross-referenced data from about 200 medical examinations, including metabolic, functional and immune traits of these mice over the rest of their lives.
Researchers found that eating a reduced diet increased life expectancy of the mice. This was the conclusion for all rodents, with responses proportional to the degree of restriction, but only caloric restriction significantly reduced the rate of aging.
Even those who underwent the 40 percent fewer calories plan saw an improvement in their life expectancy. Calorie reduction, therefore, influences life expectancy, but age, genetic ancestry and the body’s own resistance to this new scenario depend on it, they noted.
In addition, life expectancy was prolonged to the same extent in the lightest and heaviest mice, while those subjected to intermittent fasting with a high body weight before the intervention showed no signs of improvement in this aspect.
Genetics plays an important role
The researchers obtained mixed results. For example, the mice that lived the longest on the restrictive diets lost the least weight despite eating less, while the animals that lost the most weight tended to have low energy, compromised immune and reproductive systems, and shorter lifespans.
This wide range of results confirms that genetic background plays a relevant role, the study indicates.
Animals that were able to keep their body fat and glucose levels high lived longer. And my assumption here is that these animals have intrinsic resilience,” explains Gary Churchill, another of the study’s authors.
“These interventions are stressful and animals that are losing weight are showing you that they respond negatively to the diet. In this sense, diets simply reveal something about the nature of the animal,” he adds.
In this way, dietary restrictions impact life expectancy, but not completely, as there are nuances, such as genetics, that play a much more relevant role than previously thought.
For almost a century, laboratory studies have shown consistent results that if an animal eats less or less frequently, will live longer. However, scientists have struggled to understand why these types of restrictive diets lengthen life and how to best apply them to humans.
“If you want to live a long time, there are things you can control throughout your life, like diet, but really what you want is a very old grandmother,” says Churchill.
(With information from EFE)
: