The Benefits of the Early Bird Special

Calorie restriction and intermittent fasting are both associated with improved health and longevity in many animals. Studies with monkeys and humans are consistent with health benefits of both calorie restriction and intermittent fasting, but the studies are difficult to compare due to differences in the diet and feeding patterns in the monkey studies and the many variables inherent in any study involving humans. Mitchell and colleagues used mice to differentiate among the effects of calorie restriction, intermittent fasting, and diet composition on lifespan. Furthermore, because sex-dependent differences were observed in the monkey studies, this study used only male mice that were divided into the test groups at the same age of 4 months (young adult mice).

Two different diets were tested: The WIS diet had a larger amount of sucrose and fat and a lower amount of protein, and the NIA diet had a greater amount of fiber, less fat and sucrose, and more protein. These diets are named for the previous studies that used them when testing calorie restriction on aging in monkeys. The mice on each diet were then divided into 3 groups: One group had food available anytime (ad libitum, AL), one had the calorie-restricted diet available any time (CR), and one had the same amount of calories as the AL group but the food was only available for a short time representing a single meal (MF). The MF group represents a group that experienced intermittent fasting without a difference in total calories consumed, because the mice ate rapidly once they learned that the food would not be continuously available. The CR group represents a group that experienced both fasting and a reduction in calorie consumption.

The AL mice who had food available all the time ate continuously, both during the active (dark) period and the inactive (light) period. The MF animals consumed similar amounts of calories and had similar weights as the AL mice. However, the MF mice experienced several hours of fasting when the food was not available. The CR mice ate the fastest, eating shortly after the food was provided, experienced the longest period of fasting, and were lowest in weight. Even without a difference in weight or overall calorie consumption, the MF animals had a longer lifespan than the AL animals, suggesting that fasting even without a change in diet and calorie intake is beneficial. For each diet (WIS or NIA), the CR mice had the longest lifespan, showing that reducing calorie intake along with a long period of daily fasting has an additive benefit with regard to lifespan.

The daily circadian rhythms of life generally impose a period of fasting for most people. If asked, how to translate this into guidance for humans, I would say eat the last food of the day early in the evening, get a good night’s sleep, and eat a diet with limited processed food. Avoid those late-night dinners and opt for the early bird special. Indeed, R. Michael Anson, an author of the highlighted study recommends

Healthy food in moderation, and an early dinner without late snacks.

Highlighted Article

S. J. Mitchell, M. Bernier, J. A. Mattison, M. A. Aon, T. A. Kaiser, R. M. Anson, Y. Ikeno, R. M. Anderson, D. K. Ingram, R. de Cabo, Daily fasting improves health and survival in male mice independent of diet composition and calories. Cell Metabolism 10.1016/j.cmet.2018.08.011 (2018).

The Benefits of the Early Bird Special: Insight into Fasting and Longevity

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