Over the years I have tested some extreme diets. Each time I try something it gives me some new insight. Fasting with various regimens has been one of the most interesting things to experience the effects of. At this point I’ve completed about a dozen 4 or 5 day fasts.
Proponents of fasting claim that it is historically natural (humans adapted to be able to live without food for stretches of time), and is part of many cultural rituals for thousands of years, and that it has some biological benefits. The scientists studying longevity find fasting particularly interesting.
The longevity research on fasting evolved out of the line of research on calorie restricted diets trying to narrow down the mechanisms by which animals have demonstrated dramatically improved health and as much as 30% longer lifespans. After some time without food the human body will start autophagy – a process where the cells of the body are harvested and deconstructed. It appears as though the body knows how to preferentially autophage the least healthy cells in our body first. The hope is that this mechanism results in giving the body time to dispose of cells which might be more prone to become cancerous or may already be dysfunctional.
My personal experience with fasting cannot backup those lofty claims – they would require decades of research on thousands of participants to reach any full conclusions on the health effects. My personal experience with fasting is that it teaches you something about being hungry.
What is Hunger? It seems to me that much of what hunger is, is a trained response – like pavlov’s dog we are trained to be hungry from different triggers. Some experience it as a relation of time – “I always start to get hungry at 6pm”, other times it triggered by rituals – “Every time I walk past the refrigerator I think about food”. Sometimes it is triggered by stress or by smells. There is also the physiological triggers, your stomach sends signals to your brain when it’s empty. All these triggers can be mentally interrupted or re-interpreted – they require us to make decisions to go get food, cook something, cut something, chew and swallow although even complex tasks can be relegated to habit and happen without full conscious considerations.
If this is true, then when people say “I’m hungry” it doesn’t necessarily mean they need food.
After several days without food, it becomes apparent that emotional hunger feeling passes. There is a sense of pleasure that comes from not thinking about food, avoiding the decision fatigue of deciding what to eat multiple times per day. For me that is usually day 2 and 3 of a fast, and it is possible to go the whole day without thinking much about food or being hungry.
That phase passes eventually and results in a real hunger state, but where you don’t feel that hungry in the way you might be familiar with. Instead, by day 4 or 5 of a fast, energy to move muscles drops, and while mentally you feel decent (thanks keytones!), it takes more effort to move. Mentally it can become hard to think about anything other than food. Usually by day 4 I have introduced tea with a pinch of salt into my diet to satiate my mind.
I think the most interesting effects I have noticed while fasting have been related to my understanding of hunger and as a result I have been able to take some control over it, rather than hunger controlling me. But the secondary things I have noticed are also quite interesting. After several days into a fast, aches and pains have eased up – perhaps due to reduced inflammation.