A year without food (2012)

You will definitively feel weaker and be unable to work out as hard. Even a days worth of poorly timed meals and/or too little protein can mess my weight lifting up for the following day, and fasting quickly forces my lifting volume down substantially (though amino acids from your protein intake can stay in your blood stream for a few days, so if you've kept protein intake high, you can keep things normal through a couple of days of fasting).

But the main predictor of how quickly you'll recover your strength afterwards will be whether or not you keep up resistance exercise. After a weak of lazing about during vacation, it can take me 2-3 weeks of hard exercise to be back at my peak. After eating too little or fasting for a short while, it's mostly just a matter of getting well fed enough again. I don't have experience with longer fasts, so I can't say how much they'd affect me, but it does take time to trigger substantial muscle breakdown, and even if you do lose muscle, getting back up to the same strength is much quicker.

Thanks. I do sometimes. But I wonder how people manage to do multi-day fasts.

Everybody is different, "you are an experiment of one"...

A lot of material about fasting says that if you skip meals, you "cannot" eat back the calories you missed. This might be true in some individuals, but not for me. I have always been able to eat large quantities in one sitting ; I have been kicked out of all-you-can-eat buffets in my early 20s.

When I tried to eat once every 24 hours, I ended up eating huge meals and put on weight.

Depends on which archeologist or anthropologist you talk to.

What and how we eat since McDonalds was invented a couple generations ago does not have much relationship to what and how we ate for millions/hundreds of thousands of years.

There are some hints in how we're unable to store vitamin C, so obviously we evolved to rely on a relatively stable source of citrus. On the other hand the gallbladder seems optimized to digest large amounts of fatty meat every couple days at most, rather than none ever or small amounts every meal. Our long term iodine storage is somewhat lacking indicating a bit of coastal living / seafood would be a good idea. Given that ethanol is a systemic poison, our livers seem well evolved to get rid of it compared to other systemic poisons, indicating a modest consumption is probably reasonable, although not drinking is probably wiser. Our unimpressive long term iron storage, at least for women, indicates a reasonable source of iron (meat?) be hunted down and consumed at absolute minimum every month or so.

Now you can use modern high tech living to hack what your body was evolved to do, for moral or ethical or profitable reasons. We've got a ridiculously complicated world wide food production infrastructure, and a pharma infrastructure, and lots of scientific knowledge, so why not hack the system and go vegetarian even if its un-natural. Or occasional weird processed stuff. But the modern ability to hack it, doesn't mean the body doesn't have an inherent set of design constraints WRT nutrition. And occasional fasting does seem biologically part of the design. Otherwise we'd simply keel over and die once the initial blood sugar dropped too low, because it would be evolutionarily simpler to insta-pee out as ketones any fat or excess carbs consumed at the time of consumption... Aside from the obvious evolutionary positives of being lighter and faster. So we're built to pig out for a month and starve for a month.

Actually he described it quite well. Appetite is psychological, whereas hunger is a physical sensation of pain.

I'm replying to your post because I get hungry even quicker. I had lunch (rump steak, potatoes) at 1pm and now at 4:30, I'm hungry again. My BMI Is 21, with rather low body fat.