Single Status Update
So I decided to try food fasting for a week, because why not. Currently sixth day without any meal intake, just regularly drinking mineral water and vitamin pills once a day. Lost like 6 kilograms already, although roughly 3 will be back almost immediately after fasting is over - biochemistry is a bitch. Surprisingly, no hunger feeling whatsoever since lasting through first day. I was expecting at least 2 or 3 days to be rough on willpower. Generally just feeling dizzy for a little while after changing positions like getting up from chair and it's easy to get physically exhausted (after 7 km walk I was completely drained out). Uh, that's about it.
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Mr. Freeze said:
When you go for long periods of fasting, your metabolism slows. When your metabolism slows, it takes longer to process food. Meaning when you do eat again, you'll burn calories slower, and have less energy- two things that are important to losing weight. You might have *temporary* weight loss, but you'll earn it back and have no real progress to show.
Metabolism doesn't slow down. It changes, sure, but if it actually slowed down, you would most likely go extinct. Brain needs to be permanently fully energetic, otherwise bodily functions will fail. Allow me to put my point of view on the matter.
The term energy itself is on a chemical level an ATP molecule, which is in simpified terms what makes possible every single process in human body could happen. Metabolism is what makes ATP out of stuff you eat. What we usually eat can be summed up as three things - proteins, sacharides, fat. All three can be used as a source of energy, or in other words an ATP molecule can be synthetized from them. There is one problem, however, that brain cells are dependant on glucose (sacharide) even after engaging starvation (to make ATP). You can make it through with glucose level in blood roughly through one day of fasting, however not more. Another problem is that body can't synthesize glucose from fat, only from proteins. Liver starts to sythesize glucose from aminoacids of proteins in your muscles after first day of fasting, therefore for a little while your muscles will reduce, but since your muscles are the most important part of body when getting to the actual food, it would be a suicidal to go on fasting if there wasn't something more to it. The something more to it is that your liver start to produce ketones from products of metabolism of fat (acetyl-coa) which get released to blood. By the time of third to fourth day of fasting, brain adapts to this by synthesis of suitable enzymes to use ketones as a source of energy. The upside of this from diet point of view is that ketones are a BAD source of energy, because it completely replaces ATP for something less effective and therefore there needs to be many of them to keep brain fully energetic. In other words, you lose fat rather rapidly, but you feel weak. That's why it's the amount of fat that is the main factor in keeping you alive during starvation. There are also diets (called ketosis diets) that allow you to eat, but you have to strictly minimize fat and sacharide intake to allow ketose synthesis to happen. I've heard of fat people being on diets utilizing ketones from fat for a period of whole year.
When you get back to casual day rhythm from fasting, your reserve of glycogen (a storable form of glucose in liver) will be slowly built back along with some proteins that were used up before ketosis, which would roughly equal to 2-3 kgs in my case, but I currently lost 7. If somebody says you gain it all back, it's a lie. Everything else depends on how you maintain yourself afterwards, for example certain bit of movement to get rid of excess energy daily.
Also, I ended with the fasting today so I'm curious how will things turn out it upcoming days.