Sat, Aug-03-19, 12:13
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Senior Member
Posts: 4,074
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Plan: Very LC, Higher Protein
Stats: 227/186/185
BF:
Progress: 98%
Location: Herndon, VA
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Quote:
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Originally Posted by GRB5111
I was particularly interested in the explanation of the mechanism benefits of autophagy. Periodic cleansing is healthy. From previous information, autophagy starts anywhere from 16 to 20 hours after the start of a fast. Small amounts of protein or amino acids quickly shut down authophagy and glucagon levels.
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In the interests of maintaining accuracy of my posts on this forum, I need to temper the above statement stating that "autophagy starts anywhere from 16 to 20 hours after the start of a fast."
Here's a different view from Dom D'Agostino's blog regarding fasting. Autophagy and rate of starting after beginning a fast is addressed in the Take Home Message at the end of this topic:
Quote:
Fasting is a very cut and dry approach to activate autophagy, there’s no questioning which foods to eat and what to abstain from to keep these inhibitory pathways at bay. So, in some ways, fasting is the easiest approach, although I’m sure easy is not what you were thinking since generally speaking, no food = no fun. Multiple studies have demonstrated the neuroprotective effects of calorie restriction and fasting as means of removing toxic molecules and damaged mitochondria from neurons [5], and autophagy is the key player. In one particular study using an animal model, autophagy was upregulated after a 24 hour fast, and results were even more dramatic after 48 hours [6]. With that being said, this was done in a rat model, and fasting hours cannot directly translate to humans, so this information is more informative than practical. They also did not test prior to 24 hours, so it is unknown after what amount of hours autophagy begins activation. The “minimum dose required” would be great to know, because I’m sure we can all agree that reaping the benefits of a 24 hour fast in something closer to 12 hours sounds a lot better than going an entire day, or maybe 3, without eating. As of right now prolong fasts (~3-5 days) are likely what is needed to really enhance autophagy. We believe the research on that forefront will soon be available, due to the current interest in autophagy.
If we are only focused on insulin and mTOR then intermittent fasting is a more realistic strategy. The most common forms of intermittent fasting studied include alternate-day fasting and time restricted feeding, where you alternate between eating normally one day and restrict to ~500 calories or less the next, or eat all of your daily calories in a 6-8 hour window and fast the remaining, respectively. These methods may have some benefit on autophagy by giving our bodies periods of time without food and therefore downregulating our nutrient sensing pathways that, when activated, inhibit autophagy.
Take home message: It is clear that fasting activates autophagy in animal models, it is unclear however how long humans need to fast to activate autophagy. ~3-5 days likely guarantees some autophagy action, but prolong fasting is not for everyone and intermittent fasting may be an alternative.
Link: https://www.ketonutrition.org/blog/...ellular-upgrade
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The 16-20 hours was from a Fung statement in the past 6 months. This is clearly different from the blog post quoted above dated August 5, 2018. If anyone knows of a clear statement as to when autophagy starts in humans in the absence of food, I'd be interested. As stated in the D'Agostino blog post, it would be nice to know how long it takes to benefit from optimal autophagy. I would be able to determine the necessary duration of an IF for maximum benefit.
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