https://www.ncbi.nlm.nih.gov/pmc/articles/PMC535723/?page=9 “liver and kidney metabolism during prolonged (30+ days) fasting”. Again, not relevant to autophagy directly, but shows glucose, ketones (all) free fatty acids and insulin over many weeks.
“liver and kidney metabolism during prolonged (30+ days) fasting”. Good stuff, Michael. From way back in 1969 too - and one of the authors is George Cahill, who did a bunch of good work.
https://thehealthsciencesacademy.org/wp-content/uploads/2015/07/Fuel-Metabolism-in-Starvation_ReviewArticleTIMM2008-9Lazar-1.pdf – This one is biographical in the beginning, but on page 5 - 6 it gets into some cool information.
Urinary nitrogen excretion fell to 4–5 grams/day, and catheterization of the jugular, as we expected, showed some two thirds of brain fuel consumption to be D-β-hydroxybutyrate and acetoacetate
a normal adult human could survive two months of starvation; an obese person could survive much longer.
There’s also a good bit about just how excellent a fuel ketones are for us.
It would be a different deal if it involved people taking drugs and/or buying supplements, etc.
I’d gladly volunteer to have tissue samples taken while fasting, to have the autophagosomes counted…
I know exactly what you mean! I have not measured ketones in many years although in the beginning the urine strips worked well. The cheap breathalyzer (I have two) barely registers for me even after a few days fasting. I know the taste, it is not just in the morning but any time I know I am in ketosis. I also get very slightly nauseous if I have not eaten and it always accompanies that taste. It is not fruity and not really metallic but that is the closest description. Will update the next time it happens
Personally, I enjoy fasting and it does not feel like starvation, deprivation or anything unhealthy.
I don’t care whether anyone else does or not - none of my business - but I am happy to share my own experiences to anyone who asks.
I love the quiet, empty, calm feeling on day 2. It’s amazing how much energy and processes it takes to digest food!
And I also enjoy a break from deciding what to cook, cooking, dishes, etc. for a day or two…
I do hope there are some health benefits as I could sure use some internal repairs after years on a SAD diet. I know my “age spots” didn’t start to fade on my arms until I started fasting and the loose skin I have had for years has tightened up after I started fasting.
If I may ask, how long did it take before you noticed that the loose skin tightened up?
I’ve got to tell myself some of what I find objectionable might just come with the calendar. I’m 67 and it just comes with age. OTOH, I sure wouldn’t object to losing some of it, and some of the “spare tire” that feels like a balloon with a little water in it.
I’m doing Alternate Day fasts again this week, and just broke my fast at the 44-1/2 hour mark. I guess my question about autophagy is whether there’s much more benefit doing my other routine, which is about 65 hour fast, Saturday night to Tuesday some time, followed by a Wednesday after dinner to Friday fast like today’s. My tentative conclusion was it’s probably better to do the long/short fasts in a week rather than the 3 ADFs, but hard to quantify.
It took about 9 months and I was doing a 72-hr fast about once a month. I lost some on my belly and some on my upper arms aka “bat wings” LOL.
I agree with age being a factor - I am 62. I will add that I haven’t seen much more improvement over the additional skin tightening but I also haven’t been fasting much during the past 18 months due to COVID changes in my job and lack of travel.
If you’re looking for autophagy, my guess is the longer ones are better. I believe Fung’s fasting group advocates the shorter ones normally, though. I think they’re easier to do.
I have to admit, though, that it’s possible to overdo fasting. I had to stop for a while, as I was getting way too cold. It took me a long time to recover from that.
I’m trying 2x36 hours this week. I’ll be lucky to make these.
I heard this interesting use of metformin and fasting and cancer. Supposedly, metformin helps “starve” cancer cells when fasting. Hasn’t been reproduced in humans, though.
My lowest insulin test was 4.5 days into a fast. Just said “<3”. Unfortunately, I did not get it tested at the start of the fast.
But my point is that GKI for some of us is completely useless. I’ve been keto too long. I never get the best GKI values. Pretty much ever.
I am with the majority it seems. It takes XX hours to get into autophagy. I would rather stay in for many hours than repeat the cycle again and “waste” fasting time to get back into autophagy. Of course, I use normal TRE time to lower my Insulin and glucose, but…in terms of just autophagy it is not being used as wisely for that one purpose.
That’s an interesting article.
The author brings up metformin being well tolerated in general and says,"Fasting may also be difficult for some cancer patients, particularly if they are also undergoing chemotherapy, but in some cases, the ability to use a well-tolerated drug like metformin in combination with fasting may lead to a much less painful treatment regimen than many that are currently available. "
I’ve heard one of the doctors talking about keto for cancer saying it’s possible the mechanism that makes chemotherapy work is many patients get so sick they can’t eat and so they “automatically” go into ketosis from fasting.
You know how the GKI is supposed to be the key to killing cancer? Same numbers as deep fasting for autophagy.
That’s an interesting quote from the doctor. Possible, too.
I think autophagy is complex enough that I no longer try to figure it out, other than limiting calories to near zero (still have black coffee, tea) when I’m fasting. And throwing in longer fasts when I can, hoping they have an anti-cancer effect. (May even test that metformin technique, if I can get some metformin. Have to see what side effects there are, though.)
For instance, exercise and autophagy:
When you fast for 4+ days, what is the shape of your GKI curve near the end of the fast? Does it go up for a day or two, then start to fall consistently to a plateau? If not, what is the shape/pattern (if any)?
If it never plateau’s in any real sense, then I get it - seems less relevant. If yours is plateauing at a GKI of 2, then I would look at the plateau as your guide and not fret over the magnitude of the GKI when it plateau’s. Just because someone can get a GKI of 2 while eating, does not put them into the same category of a GKI of 2 fasted for 5 days.
And an interesting article on exercise and autophagy.
He does a section on fasting and cardio exercise together being good for it, and that’s my routine. I always ride fasted because even my non-fasting days are TMAD and I ride before the first meal.