The interesting thing about intermittent fasting is that it seems to work through a different but overlapping set of molecular mechanisms to calorie restriction. The gene expression profiles in rodents say that the way in which intermittent fasting (such as alternate day fasting, the most commonly studied mode) works to alter metabolism into a better running state is not quite the same as the mechanisms of straight calorie restriction.
So evidently you still have upregulated autophagy (i.e. better housekeeping in cells), the levels of methionine in the diet are going to be lower thus triggering that important switch in the metabolism of calorie restriction, more ghrelin floating around to stimulate the immune system, and so on. But it's not running the same way as for a steady low diet, and that appears to make some differences. Intermittent fasting is not as well studied as calorie restriction, but it is shown to extend life in mammals, and it is certainly easier to manage for most humans:
Which means to say that you'll probably obtain health benefits by doing it, but the studies that show massive health gains and enormously lowered risk of age-related disease for calorie restricted humans may or may not apply to you.
Great point; I've been thinking about this for some time. Would love to have more data, though! I'm also interested in any metabolic similarity either influence has to endurance athletics.
Exercise and calorie restriction both influence autophagy. In fact pretty much everything that extends life in laboratory animals boosts autophagy one way or another - such as through altered expression levels of heat shock proteins and related regulators. You'll find that foundational study on exercise mimetic drugs looks at heat shock protein manipulation more often than not.
There is no consensus on whether different types of aerobic exercise are better or worse for longevity, or whether more than the modest 30 minutes a day is better or worse for longevity. Elite athletes have a massive longevity advantage over the rest of the population, for example, but that can just as well be explained by the fact that you have to be robust to become an elite athlete in the first place.
Exercise also works through hormesis and reactive oxygen species signaling - which is why flooding your system with ingested antioxidants can destroy some of its benefits:
http://www.fightaging.org/archives/2010/05/intermittent-fast...
http://www.fightaging.org/archives/2009/11/a-little-intermit...
So evidently you still have upregulated autophagy (i.e. better housekeeping in cells), the levels of methionine in the diet are going to be lower thus triggering that important switch in the metabolism of calorie restriction, more ghrelin floating around to stimulate the immune system, and so on. But it's not running the same way as for a steady low diet, and that appears to make some differences. Intermittent fasting is not as well studied as calorie restriction, but it is shown to extend life in mammals, and it is certainly easier to manage for most humans:
http://www.fightaging.org/archives/2009/02/practicing-interm...
Which means to say that you'll probably obtain health benefits by doing it, but the studies that show massive health gains and enormously lowered risk of age-related disease for calorie restricted humans may or may not apply to you.