I had some thoughts after reading the recent thread about skin tightening as a by product of fasting and autophagy. Clearly we don’t know a great deal about the process of autophagy (in regards to when it begins during fasting, to what extent it affects our over all health, it’s role in aging, etc). But we do know that it is a process of breaking down damaged or “old” cells and that it appears to be amplified by being in a fasted state. As someone who experienced the deleterious effects of having had anorexia as an adult (and having been keto during that time) I think I have a unique perspective on how autophagy can potentially cause negative health consequences and why it might not always be a beneficial state. When we fast and our body starts using its own stored energy, there are repair process taking place, but it is also in a state of catabolism, and this will vary depending on the person’s body composition, metabolic health, activity level, main source of energy substrate, age, etc. When I was underweight and had anorexia (and under fat, sub 10% body fat) and eating keto, I engaged in high levels of exercise and was fasting for about 18 hours a day. I didn’t know anything about autophagy then (about 3 years ago) but I noticed that my skin tone improved quite a bit. I was, at my lowest point, about 80 pounds less than I was at my highest weight when I was pregnant with my first child (about 10 years earlier). So I had some “Mom jiggle” on my tummy from gaining and losing weight during two pregnancies. This toned up quite a bit though. During that time, I was eating a more moderate amount of protein (currently I am eating a lot more) and eating lots of salads and fats. So based on the amount of exercise I was doing and my lean body mass, i am sure I was not taking in sufficient protein. As I became leaner, I had the skin tightening but also my hair was not as healthy and the skin on my hands cracked and bled. I know my organs were also affected, many people with anorexia experience their heart shrinking. So my theory is my body probably did scavenge energy (protein) from skin cells but it also turned to things like organs when I was basically starving to death. My point is, I was in a catabolic state due to the anorexia, I was starving and whatever substrate my body hunted down once my body fat stores were tapped was the result of last ditch efforts to attack vital organs further. So in my case, autophagy was reflective of my body being in a stress state. I can’t help but wonder if this might be the case even for people who have sufficient body fat stores who engage in longer fasts. I think that, while autophagy clearly has some positive effects as far as helping cells stay healthy, it also might signal to the body that it’s in that catabolic state, which is inherently stressful. So engaging in EF over the long term might cause a state of stress for the body and lead to consequences including lowered metabolic rate (reduced thyroid function), increases in hunger signals (due to the body believing its in a state of relative starvation), and changes in organ size/function. This is a super long post…but I wanted to share my thoughts as this is a controversial topic that we don’t have definitive answers for. I just wanted to offer my perspective that autophagy might not be without health consequences when people intentionally engage in EF over a long period of time to try and induce further “cellular cleaning”
Fasting, autophagy, and catabolism
Interesting thoughts, and some real concerns on how can we protect organs while hoping our bodies use up all the useful skin protein just “hanging” around.
K
@Emacfarland I follow you totally. When you talk about the risks of EF when not in possession of sufficient body fat - I can totally see it. However, a bunch of us 'regular fat" peeps have sufficient fat to provide the needed REE. at 31.5 cals/lb/day, one only needs about 60 lbs of fat to provide the average 2000 kCals a day. Even a not overweight 150 lb person is carrying 30 lbs fat (20%), so 60 lbs is easy if only slightly overweight - ie 5’7"-5’9" and 180-200lbs total weight.
I, of course, am ‘gifted’, in that I have 100lbs of total fat - so I am all set for the next 40lbs of fat loss 