Just wondering - why is eating <500 calories a day considered dangerous, but fasting for extended periods of time is okay?
Your body will go into a “fat eating” mode after not getting a new source of energy put in it (food). If you don’t eat you’ll stay in that state. If you eat however ,you’ll be jumping in and out of that mode.
I’m Not quite sure if it’s DANGEROUS to eat that little( someone find me a source?) but I’d say from experience at least, it’s easier to just go without food than to dip in and out.
Not eating at all will put you on a fat burning mode (you will not be hungry at all)
Eating very little will starve you (you will be extremly hungry and your basal metabolisme will decrease)
&#x200B;
Watch the videos of the Dr Jason FUNG on fasting for more details.
Rather than a metabolic answer, would an evolutionary answer be interesting?
The human body evolved to survive various challenges. One of these was to hunt for food in times of scarcity, during which the body needs to be on top form while it pursues its prey. When doing this, humans wouldn’t have any food - they are hunting because they have no food, and they won’t be pausing to forage. This is replicated by a fast.
During this time, the body should give itself more energy, and set the body up to follow its prey single-mindedly. This is often replicated in studies - those fully fasting have more energy, need less sleep, have a higher metabolism. While unneeded cells get broken down, various hormones kick in to keep muscle mass up, so we can catch the thing we’re hunting.
Then there’s what the body should do when there’s nothing to hunt, and we’re living off meagre portions, getting between 200-800 calories a day for a long period. Maybe this is because there’s been a drought in the area, or heavy snow killing off everything else. We’re picking at the odd things we can forage, eating the nutritionally crap options that remain (tree bark etc).
In this case, the body needs to reduce its energy use to the bare minimum, to balance what we’re taking in. It doesn’t want to use its fat stores, as those are reserved for the next time there’s a chance of a reward, and using them up to get through a lean time might result in there being nothing left. As such, all unneeded metabolic processes are shut off - nail growth, hair growth, immune systems, organ renewal.
TLDR: fast makes you a hunter, severe restriction makes you weak.
Sources: Summary texts “Why we get fat” by Gary Taubes, and “The Obesity Code” by Jason Fung, with some follow up reading of their references.
There are programs out there with 2-12 weeks below 800 kcal, after that 2:5. I got inspired by that.
I just need to drop 8kg and wants to do it quick. But fasting for 10-12 days to get it off is not realistic for me (have not been able to go beyond 5 days)
So I do 600 kcal per day in one sitting and I am now on day 7 down 4 kg.
It does not feel much worse or better than 100% water fast, but mentally it is easier knowing that I can get a full stomach once per day. And if you eat vegetables, 400-600 kcal can fill you up. Onion soup, tomato soup, salads etc are great.
Of course you probably cannot get the same autophagy benefits but I have unlocked the 5+ day fast mimicking and I do not have to start over with a fast again and again (first days are the worst).