the neuroendocrine system and those related to the improvement in glucose homeostasis can be attributed to decrease in adipose cells and their products.Probably too simple and above all difficult to treat with a drug and thus not profitable enough to be accepted by the medical establishment. Now, if this would be the case, intermittent fasting would in fact provide the sought-after silver bullet to leading a leaner, healthier life, as both the anecdotal reports on the Net, as well as the the majority of the studies that have been cited in this, as well as the previous installments show quite conclusively that going without food for periods <24h is capable of reducing body fat stores, while preserving lean muscle (and bone) mass. But why, or better how does that work?Intermittent fasting, fat reduction, health improvements and the cyclicality of lifeIllustration 1: It probably is the magic interplay of AMPK and mTOR that produces such remarkable transformations as Duong Nguyen's. We will delve deeper into the their reciprocal interaction in the next installment of the Intermittent Thoughts on Intermittent Fasting SeriesDue to its cyclic nature intermittent fasting seems to temporarily produce similar "reductions in protein synthesis" (Barrows. 1978) as the ones which have been established as the fundamental mechanisms of the life-extending effects of calorie restriction as early as in the late 1970s and of which we know today that they partly mediated by an AMPK-induced downregulation of the mTOR pathway. In that, this transient AMPK response to intermittent fasting, which most intermittent fasters further stimulate by exercising in a (semi-)fasted state, appears to be profound enough to stimulate or, according to some recent research (cf. Canto. 2010), we should probably say "sustain" the SIRT1-pathway to an extent that allows dieters to benefit from its immediate fat-mobilizing effect on white adipocytes (Picard. 2004) and its ability to maintain telomer length (and subsequent longevity, cf. Palacios. 2010) without the unwanted muscle-wasting side-effects of prolonged fasting periods.The fasting induced AMPK expression is yet only one part of the cycle, of which we have learned in this installment that it is responsible for both, the "cosmetic" effects on body fat, which could, after all, be causative and not just corollary or even subsequent to improvements in insulin sensitivity (cf. What Comes First: Inflammation or Obesity?), lipid profiles, and the whole string of beneficial health effects which irrefutably contribute to the longevity effect of inhumane low-calorie diets. In view of the fact that another valuable Sunday afternoon is drawing to a close, the discussion of the second player in this cycle, the mammalian Target of Rapamycin, or in short mTOR, will yet have to be postponed to the next episode of the Intermittent Thoughts on Intermittent Fasting Series - so stay tuned, keep the questions and comments coming and don't forget to check back on Thursday to see what AMPK and mTOR are doing to our man at the 2012 wheelchair nationals, Adelfo Cerame!Image 1: Any roundworms reading this? I hope you know that by not eating enough and feeling miserable you can extend your lifespan ;-)Thanks