Studies have shown that restricted eating is linked to improved longevity. In a recent study, researchers explored how eating less could extend lifespan and discovered that those who experienced the least weight loss while eating less had the greatest longevity benefits.
According to the results of the mice study published in Nature, eating less food or less frequently improved longevity. However, consuming fewer calories significantly impacted lifespan more than periodic fasting. The results revealed that mice on very low-calorie diets lived longer, regardless of their body fat or glucose levels, which are common biomarkers of metabolic health and aging.
"Our study really points to the importance of resilience. The most robust animals keep their weight on even in the face of stress and caloric restriction, and they are the ones that live the longest. It also suggests that a more moderate level of calorie restriction might be the way to balance long-term health and lifespan," said Gary Churchill, who led the study in a news release.
The researchers examined a group of genetically distinct mice on five different diets: one in which the animals could eat freely at any time, two in which they received either 60% or 80% of their baseline calories daily, and two in which the animals fasted for one or two consecutive days each week but ate as much as they wanted on the other days. The mice were then monitored for the rest of their lives through periodic blood tests and thorough evaluations of their overall health.
"Overall, mice on unrestricted diets lived for an average of 25 months, those on the intermittent fasting diets lived for an average of 28 months, those eating 80% of baseline lived for an average of 30 months, and those eating 60% of baseline lived for 34 months," the news release stated.
Mice that naturally maintained their body weight, body fat percentage, and immune cell health during periods of stress or low food intake, as well as those that did not lose body fat later in life, had the longest lifespans.
"While caloric restriction is generally good for lifespan, our data show that losing weight on caloric restriction is actually bad for lifespan. So when we look at human trials of longevity drugs and see that people are losing weight and have better metabolic profiles, it turns out that might not be a good marker of their future lifespan at all," Churchill explained.
Among those eating the fewest calories, some mice lived only a few months, while others lived up to four and a half years. The researchers who examined the reason behind the wide range realized that genetic factors played a much larger role in lifespan than diet, particularly genetically encoded resilience as a critical factor.
"If you want to live a long time, there are things you can control within your lifetime such as diet, but really what you want is a very old grandmother," Churchill said.
