Reviewing the Benefits of Intermittent Fasting
The paper noted here discusses a range of studies assessing the ability of forms of intermittent fasting to improve long-term health and life expectancy. Results are generally positive, but one should expect long-lived mammals to exhibit smaller gains in longevity than are observed in short-lived mammals, following the known outcomes of calorie restriction. Intermittent fasting is not as well studied as the practice of calorie restriction, but does appear to work via a similar set of mechanisms, even when overall calorie intake is not much reduced. Time spent in a state of hunger, and the metabolic changes provoked by hunger, are perhaps the important mechanisms shared by the various forms of dietary restriction.
Intermittent fasting (IF) is an eating pattern in which individuals go extended periods with little or no energy intake after consuming regular food in intervening periods. IF includes alternate-day fasting (ADF), modified fasting (MF), time-restricted fasting (TRF), and fasting-mimicking diet (FMD). Studies showed that IF increases the average lifespan of rats by 14-45% and mice by only 4-27%. Further, dietary restriction increases fatty acid oxidation by maintaining mitochondrial network homeostasis and functional coordination with the peroxisome, thereby promoting longevity.
Clinical studies demonstrated that long-term IF improves cognitive disorders and reduces oxidative stress in middle-aged adults. It also delays the onset of age-related brain damage. Moreover, nutrient-sensing signaling pathways such as the AMPK, SIRT1, mTOR, and insulin/IGF-1 pathways are downregulated during IF, blocking cell proliferation and activating stress factors, thereby negatively regulating various aging signals. IF can also protect the heart from ischemic damage, reduce body mass index and blood lipids, improve glucose tolerance, and reduce the incidence of coronary artery disease by increasing levels of the growth hormone. This in turn increases lipolysis and insulin secretion in addition to reducing other glucose metabolism pathway markers.