The metabolism of mice and rats is very sensitive to the stress of hunger; cells dial up their recycling and maintenance activities in response, and over time this adds up to a significant benefit to health and longevity. Calorie restriction has a sizable effect on longevity in short-lived rodents, but then so does intermittent fasting, even if the overall calorie intake is kept to the same level. Researchers here explore the lower end of this effect, using scheduled feeding to create comparatively short daily fasts between meals. This still produces health benefits.
Increasing time between meals made male mice healthier overall and live longer compared to mice who ate more frequently, according to a new study. Health and longevity improved with increased fasting time, regardless of what the mice ate or how many calories they consumed. "This study showed that mice who ate one meal per day, and thus had the longest fasting period, seemed to have a longer lifespan and better outcomes for common age-related liver disease and metabolic disorders. These intriguing results in an animal model show that the interplay of total caloric intake and the length of feeding and fasting periods deserves a closer look."
The scientists randomly divided 292 male mice into two diet groups. One group received a naturally sourced diet that was lower in purified sugars and fat, and higher in protein and fiber than the other diet. The mice in each diet group were then divided into three sub-groups based on how often they had access to food. The first group of mice had access to food around the clock. A second group of mice was fed 30 percent less calories per day than the first group. The third group was meal fed, getting a single meal that added up to the exact number of calories as the round-the-clock group. Both the meal-fed and calorie-restricted mice learned to eat quickly when food was available, resulting in longer daily fasting periods for both groups.
The scientists tracked the mice's metabolic health through their lifespans until their natural deaths and examined them post-mortem. Meal-fed and calorie-restricted mice showed improvements in overall health, as evidenced by delays in common age-related damage to the liver and other organs, and extended longevity. The calorie-restricted mice also showed significant improvement in fasting glucose and insulin levels compared to the other groups. Interestingly, the researchers found that diet composition had no significant impact on lifespan in the meal fed and calorie restricted groups.