Experiments with lab mice show that if you reduce their caloric intake by 30 to 40 percent, the mice typically live 30 percent longer. The goal is to reduce caloric intake enough to cause biological changes without malnourishing the mice. Experiments with worms and monkeys show similar results, reports Dana G. Smith for The New York Times. If we eat less, will we live longer?
The jury’s out on the value of eating less for humans, but it’s fascinating to learn about the consequences of eating less for mice and monkeys. Beyond often living longer, it appears that limiting calories in lab mice and other animals also reduced their risk of developing cancer and other serious health conditions that tend to appear as we grow old.
What is not known? It’s not clear the principal cause of longer life expectancy from animals consuming fewer calories. Is it the number of calories consumed or when the calories are consumed that is most important? And, there’s no meaningful data to indicate that eating less helps human beings live longer.
Why would eating less extend an animal’s or a person’s life? It’s not well understood. Some believe that consuming fewer calories enables animals to be more resilient to outside stressors. Researchers have found that lab mice that consume fewer calories are better able to resist toxins and heal more quickly after being hurt.
Some believe that people who consume fewer calories have slower metabolisms. Perhaps requiring your body to metabolize less allows it to live longer. “You know, just slow the wheels down and the tires will last longer,” said Dr. Kim Huffman, an associate professor of medicine at Duke University School of Medicine who has studied calorie restriction in people.
Also, if you take in fewer calories, your body will need to rely on sources of energy other than glucose. It could eat up cells that are not functioning as a source of energy. As a result, cells work better, reducing the likelihood of age-related disease and potentially extending life.
Of note, the research finding eating less leads mice to live longer is not dispositive. A few researchers found that mice and monkeys sometimes lived shorter lives when they ate less. Other researchers dismiss these findings because of the abundance of evidence to the contrary.
Some believe that intermittent fasting could play a principal role in longevity. In a monkey trial in which the monkeys only received one calorie-restricted meal every sixteen hours, the monkeys lived longer. In another monkey trial in which the monkeys received two calorie-restricted meals a day and could eat them whenever they pleased, the monkeys lived less long.
Intermittent fasting and a low-calorie diet led mice to live 35 percent longer. Mice that had a low-calorie diet but could eat at any time of the day lived 10 percent longer than those with a full-calorie diet.
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