Cutting caloric intake by 30 to 40 percent can significantly increase the longevity of lab mice, with research suggesting a similar impact on a variety of species. This calorie restriction has been linked to a lower likelihood of developing cancer and other age-related diseases in animals, but the mechanisms behind these effects are still debated. Some experts believe that calorie restriction makes animals more resilient to stress, slows down metabolism, and promotes metabolic health and longevity by forcing the body to rely on alternative fuel sources.
While the majority of animal studies support the idea that calorie restriction extends lifespan, there are exceptions. Some studies, such as one conducted on genetically diverse mice, have found mixed results. Similarly, long-term trials on monkeys have produced conflicting findings on the benefits of calorie restriction. However, research indicates that intermittent fasting, or reducing one’s eating window, may be equally important as the number of calories consumed in promoting longevity. Studies on mice have shown that intermittent fasting alongside calorie restriction can significantly increase lifespan.
It remains uncertain whether calorie restriction and intermittent fasting can lead to increased longevity in humans. The Calerie study, which examined the effects of a 25% calorie reduction in healthy adults over 2 years, found improvements in cardiometabolic health and a slower rate of aging among participants who achieved an 11% calorie reduction. Research on intermittent fasting has shown short-term benefits in improving metabolic health and reducing inflammation in people with varying body mass indexes, but the evidence on long-term lifespan extension is inconclusive. Some studies have even found that overweight individuals may have a lower risk of death compared to those with a normal or underweight classification.
Despite decades of research, experts are still unable to definitively confirm whether the longevity benefits observed in animals will apply to humans. While there are reasons to believe that calorie restriction and intermittent fasting may promote longevity and offer short-term health benefits, there is still much unknown. Further research is needed to clarify the effects of these dietary interventions on human lifespan and to determine the ideal strategies for maximizing healthspan and longevity.
