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Comment by paulgerhardt | Hacker News Reader

Recently didn't eat for 40 days and didn't notice this. Suspect there's some issues by putting the mice on calorie restriction vs fasting. Ie "the researchers fed the mice right before the experiments" - if you're in a fasted state and do introduce food you're going to create an insulin spike - if you were also previously calorie deprived you could go hypoglycemic right after.

Going back as far as the Minnesota Starvation Experiment it appears in certain survival instances calorie restriction is worse than no calories. [1]

[1] https://en.wikipedia.org/wiki/Minnesota_Starvation_Experimen...

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Ok. How did you not eat for 40 days and why?

I heard you can go without food for 30 days. My longest fast was 3 days and while I liked it, I function much better with food.

I did it back during Covid. I did it imperfectly (just water initially - don't do that, see below). It looked like a vaccine was two years out, getting covid was inevitable, and the outcomes of getting sick were not good for obese people. At 28 bmi I figured the best thing I could do was lose weight, wear gloves, mask up, not travel, and expose all my mail/packages to UV light. Made sense at the time with the lack of empirical evidence we had then and needed to work from first principles. This was March of 2020.

Longer thread on the subject: https://twitter.com/pmg/status/1463309372793057285

tldr; We store fat to get us through periods of lack of food. Bears do this too. We literally have a "machine" inside us that we evolved at great expense that gets us through periods of no food. Fat storage is an "extra" feature - not the default. Chimps and gorillas don't have it for instance - if you've seen one, they're basically ripped, no real fat storage - probably because we evolved on the savannas (or similar environment with seasonal food scarcity) and they evolved in the jungle where food was always present.

Simple (not easy) fat loss guide: drink water, supplement with essential vitamins and minerals that you don't store naturally in fat (i.e. sodium, potassium, magnesium, b vitamins, and vitamin c). As I understand it, most other vitamins are fat soluble and thus...stored in fat. No, you don't lose much muscle (I lost 0.1%) - I believe because the body makes an exogenous amount of HGH when fasting (but not during calorie restriction). Currently of the mindset short term fasting (less than 7 days) is better than calorie restriction for weight loss. Long term fasting (15+ days) has mild negative outcomes but is an appropriate option when the alternative is death by "X" - included co-morbidities caused by long term obesity. Sustained vitamin deficiency over months or years (anorexia) can cause worse outcomes than obesity. A "one and done" fast is not that.

Did you feel very overweight at BMI 28?

I have a BMI of 28.5 (6'0, 210 lbs) and I'm pretty lean, active, and healthy. I have denser bones and a bit more muscle than average, but my body isn't _that_ unusual.

Good for you on using covid as motivation to get healthier.

Objectively, yes. A bunch of things in a q.bio report made it hard to do that self-rationalizing thing where "it's not great but probably fine" - i.e. high LDL ratio, high liver fat, etc.

Much happier at BMI ~21 and if I knew this path was viable I would have done it 5 years ago.

Awesome, congratulations!

> No, you don't lose much muscle (I lost 0.1%)

How did you measure this number? Unless you were on some kind of drug, this seems impossible.

A q.bio report. Basically MRI + DEXA + blood work + urinalysis. It's a few thousand dollars each go but much better value than doing all the tests as one off's (if you can even get them).

I did not supplement with any drugs but your body does produce up to 1,250% more HGH in a long-term fasted state(!). You're also completely deprived of glycogens so your ability to perform anaerobic work to gain muscle is probably not going to happen without some more bio-hackery.

I heard second hand that Tim Ferris did two long term fasts. One under medical supervision where he was confined to a hospital and lost significant muscle mass; another where he went about his normal routines and (surprisingly) didn't lose any notable mass. Which matches what we know about muscle atrophy in ICU patients for instance - confine someone to a bed and they're going to waste away.

I've seen salt-water fast plans a number of times before and wouldn't mind trying one out since I do similar short experiments every now and them myself as well. Would you please mind explaining how you figured out dosage for everything you were taking, or what the doses were for you? I've tried a water fast before, but couldn't find a good spot between over-hydrated and under-hydrated.

I should just write a post.

But at a high level.

You BOTH look at recommended daily values AND listen to your body. NIH has a decent starting point. I.e. potassium is 4,700mg: https://ods.od.nih.gov/factsheets/Potassium-HealthProfession...

There's also a fair amount of margin for error. A low effort is a salt supplement like this: https://www.amazon.com/Brain-Forza-Electrolytes-Flavoring-Un... + B complex + C vitamins like this: https://www.amazon.com/Natures-Bounty-B-Complex-Vitamin-Cell... - I don't particularly endorse any one supplement - just look up what are the essential vitamins and minerals on NIH (https://www.nccih.nih.gov/health/vitamins-and-minerals) and supplement the recommended daily amounts for the non-fat soluble ones. You can probably do without the vitamins on a short fast but you will feel miserable without the salts.

Your body is still "eating" - you're still having bowel movements for instance - but it's just eating your own fat stores which include some fat soluable vitamins. NB I did not look to see if I was getting enough from this - but when I did my blood work a few times the only thing I was consistently low on was sodium and potassium because I was under supplementing on those because drinking salt water is gross (like I said, I did this imperfectly.)

One shouldn't eat salt in pill form. I didn't try. But supposedly it burns your intestinal lining. Rather I'd mix a scoop of that into my black coffee, 4 times a day. If I had muscle fatigue I'd have more potassium. If I couldn't sleep, more magnesium. Light headed when standing? More sodium. This is the listening to your body part and if you're short on salts after two weeks you absolutely will know it. But, mixing salt in water is gross and drinking too much salt in too short of time period will give you the runs. Getting enough salt is the only "hard" part. You're still doing what one normally does as a human, just less.

I think I got it down to 2L of water. Some casual cups of decaffeinated black coffee or tea. 4 thimble sized supplements of various salts.

Thank you very much for taking the time to explain the approach you took, it's much appreciated. Last time I tried a water fast I wrote it off as I just felt absolutely garbage a very short while in, but I now understand my approach to it was too simplistic. Your tips on when to supplement more of what are invaluable, I think you should definitely take the time to write this up as a post so it gets more visibility.

Adding a teaspoon of vinegar to the solution of regular salt and Lite Salt(for Potassium) and some ice made it easier to swallow on my 5 day water fast.

Honestly this is very impressive. You definitely have what it takes to survive an apocalypse. I also think that level of caution is warranted in an unknown pathogenic environment.

Was food delivery not an option, or were you worried about that being a vector of transmission?

I read it as fasting was intentional to reduce BMI.

If you lost less than .1% of your muscle mass that's abnormal. There are 100s of studies on people losing weight and they almost all lose some amount of muscle mass.

>My longest fast was 3 days and while I liked it, I function much better with food.

Three days is the longest people should go for if they haven't tried fasting before and don't have experience with gradual refeeding. Any longer than five days and you risk running into the refeeding syndrome.

https://en.wikipedia.org/wiki/Refeeding_syndrome

This is something I hear repeated without hard evidence. Plenty of people do 10+ day fasts and don’t get refeeding syndrome. I have never heard of it happening. While I can’t prove it doesn’t happen to some sensitive people in rare cases, my tendency is to think this is an urban myth. We’re not talking about holocaust victims or hunger strikers.

If you’ve practiced a normal diet and do a seven day fast you’re going to be fine.

If you’re anorexic, fast for 40 days, and don’t supplement with salts (particularly potassium) you’re going to have refeeding syndrome.

If one’s worried about it, just get ones blood work done before one starts eating again. It takes about an hour and will show you exactly what you are low on what to supplement to get to baseline. To the extent people are advising one not to do an extended fast without medical supervision - eh - basically the extent of the medical supervision is "let's run a panel every few days and see if anything is dangerously out of whack" - and maybe confine you to a hospital for the duration - but if you're not outside and walking a normal amount and say confined to a room you absolutely will lose a large amount of muscle.

There's a lot of people overindexing on the dangers of refeeding. It is important to factor in after a week (honestly more like 15+ days) but also trivially addressed.

They likely had broth/tea/vitamins.

In this study that you did on yourself, did you rigorously test your visual acuity at regular intervals?

That's risky, even if it helped you lose weight. I had a former colleague who had a long fast, he ended up losing hair and he had serious joint issues for a long while after that - it caused damage, and I'm not sure he made a full recovery.

Be careful, it’s believed ~40 days without food can kill you if you don’t take supplements. People have gone for much longer while taking supplements including salt.

This isnt a matter of believe. There are lots of prisoners who went on hunger strikes and perished from it. With them starting with a background of a normal western diet.

https://en.wikipedia.org/wiki/1981_Irish_hunger_strike 45-73 days till death with most lasting 60 days.

Holger Meins lasted 58 days despite forced feeding. https://de.wikipedia.org/wiki/Holger_Meins

List is obviously a lot longer but they offer a great dataset

Excluding salt would surely be insane, you piss and sweat out a lot of salt and that needs to be replenished. I don't see any way around that.

Of course, but someone is going to take a multivitamin and assume that’s enough.

My speculation is that the brain activates the low-power mode when it really believes that the food is scarce. However a voluntary fasting, no matter how long, would not trigger a low-power mode since your mood is still very positive and self controlled.

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