bungeejumper wrote:Fraid my brain doesn't function if I fast.
My work goes right down the drain, and I just can't focus. And I speak from regular experience. Every six months or so, I am required to do thirty hours without food for medical tests, and it's a kind of zombie existence until I can get some calories down me. At which point I finally start to wake up. Do I feel "energised" or "cleansed" or "regenerated"? Nope, I just feel ten ounces lighter and starving (and not in a good way).
So there we have it. Either I'm a fully-evolved 21st century specimen, or I'm a wimp who would never have survived the last Ice Age. Very possibly both.
BJ
I think most people would feel that way. Our bodies get used to a regular pattern of meals, not just the digestive system but the brain too. Going from say, 3 meals per 24 hours, to no meals for 30 hours once every 6 months is quite an extreme change, you're missing 4 meals. Not surprising it makes you feel under-par. If you want to get some of the benefits of fasting then you can do it gradually, using the 5:2 diet or one of the variations and then your body will become more used to the fasting period.
Brain function is definitely affected by fasting:
When you are on a keto diet, or fasting, your brain can switch from using glucose as its main fuel source to using ketones. There are however portions of the brain that do require glucose for function. The brain will use some of the carbohydrates consumed on a ketogenic diet (~5-10% of calories is the usual range of carbohydrate consumed when eating a ketogenic diet) and the rest will be produced through gluconeogenesis in the liver. During gluconeogenesis, the liver will create glucose using amino acids from protein. Glucose can also be created through gluconeogenesis by using the backbone of fatty acids, glycerol. This process ensures that the portions of the brain that rely on glucose will have their preferred energy substrate in times of fasting or very low carbohydrate intake....
Ketone bodies reduce reactive oxygen species (ROS), a type of by-product molecule that can react with other molecules in a cell. The build up of ROS in cells can overwhelm antioxidant activity and can cause damage to DNA, RNA, proteins and lipids. ROS have been implicated in aging, neurodegeneration and carcinogenesis (the formation of cancer).
https://lifeapps.io/nutrition/this-is-your-brain-on-ketones/NB the article in the above link mentions a ketogenic diet which is another thing altogether but the brain chemistry comments are accurate AFAIK.
For about the last 2 decades I've eaten only one meal each day and every 7-10 days skip a day. On the second day I can usually, but not always, notice a difference in brain and body. On my previous exercise bike I used to do regular exercises, eg 4 km 'uphill' or 10 km 'on the flat'. On fasting days I was about 2 or 3 percent slower. I've also had periods of many months when I've been programming for many hours a day. It seemed,
very subjectively, that I produced more code and better quality code on fasting days. However, although I usually feel pretty upbeat on fasting days I do occasionally feel a little irritable and have difficulty concentrating, so I kept the fasting for days when I didn't have to go to work with other people.
Personally, I think the health benefits are considerable but that's just my view.
RC