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Comment by bitL | Hacker News Reader

Waterfasting + electrolytes for a month would probably get you to -20kg. It's just the first few days until you start burning fat that are a bit weird.

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I hope I don't need to say this, but don't do this.

Have you done this? Water fasting is something you just "do for a month" nor should you casually recommend it. I've done a three day water fast and it was rough and nearly fainted on day three.

Quick wins make for quick failures. OP has found something sustainable and doesn't need a 40kg trick.

> I've done a three day water fast and it was rough and nearly fainted on day three.

More electrolytes would help with this, specifically salt. And if you drink plain water, it depletes your electrolytes pretty quickly through urination.

But YMMV, as always.

You should have tried the 4th day, usually the first 3 days are the worst, then the body completely switches to burning fat and learns how to do it efficiently. 6th day is for me usually the worst sudden crisis, then from 7th to 21st day I have absolute mental clarity, I can finish very demanding mental projects quickly and require only around 4 hours of sleep, then up to 30th I feel normal and slowly start to get hungry. After the fast I feel like after a great sauna session, but it lasts around a week. It feels like having a superpower. However, physical exercise ability goes away very quickly (I actually measured it every day and even went mountain-biking to steep hills to see how much my performance degrades and it was downhill literally and figuratively).

YMMV, but yes, with full supplies it usually takes about 3 days to deplete sugars and switch to fat.

If you're not used to keto, switching may be physiologically hard. Gradually transitioning from carbs to fat, and then or later to fasting may be easier on the body, though a prolonged hardship for the mind.

Once you get used to it, switching is a normal thing to do, though again YMMV.

I've done that multiple times (~30 days), usually after I wrap up some demanding project where I couldn't keep my fitness 100%. If you are healthy and take electrolytes properly, it's usually fine. It's not one size fits all, but I find people that reject it without any evidence uninformed about how their body actually works.

What kind of electrolytes do you take and how much?

I don't water fast so I can't speak about that specifically, but I can give a good answer on oral rehydration mixtures in general. Here's the TLDR I have in a notes file on my phone:

A drink made with 6 level teaspoons of sugar and 1/2 level teaspoon of salt dissolved in 1 litre of clean water.

Be very careful to mix the correct amounts. Too much sugar can make the diarrhoea worse. Too much salt can be extremely harmful to the child.

Making the mixture a little too diluted (with more than 1 litre of clean water) is not harmful.

Ideal consumption ~30ml every few mins (or ~90mim for the 1L)

I left the child reference in as a copy/paste from... I can't remember which medical source I got it from - although my use has only been for when I or someone else wants to minimise a hangover. I once made this mix for somebody in front of a GP (doctor) who said "wow, that's exactly the 'basic rehydration recipe' we teach when we go to parts of the world where they don't have the education / equipment we have in the UK".

But that's the MVP for oral rehydration. A little potassium is good to include, and looking at the commercial tablets I have (that mix with water) they include potassium (193mg / 200ml water) and chloride (350mg / 200ml).

I ordered various brands from Amazon and then just took 1 tablet per 1-2 glasses of water. Initially, I simply added a bit of salt to the water. Also, I usually drink ~2x more than normally because most of the water comes from food so if you keep your usual drinking levels, you get dehydrated. I believe that's why most people feel miserable (outside initial sugar/caffeine withdrawal), because they are dehydrated and the initial 10 lbs/5 kg weight loss is all just missing water. Also, taking pure chicken broth once a week might help with getting the protein that is lost back (100-150g/week).

I think if one works from home during COVID-19, then starting on Friday, going over the worst during the weekend, and then just functioning normally during the week is a perfect way to lose weight without any measurable effects on one's work performance.

I did 2x 48hrs water fasts but I couldn't manage to get any work done during the time. And it does not fix the problem of overeating once you break fast again.

Losing weight is one thing but manage the weight long term is the really hard one.

Let's ask me again in 2-5 years about it.

The first time it's difficult. I was able to get into ketosis by diet alone when I was doing workouts, so that helped a lot to overcome the first 1-3 days (basically, massive headaches on the first day and feeling weird until the 3rd day). Also, breaking the fast was basically a week-long broth and vegetables, then I switched over to mostly salad as food. Obviously, if you don't move, e.g. due to COVID-19, it's difficult to keep yourself in shape; for that I recommend a daily routine of 30-60 minutes on an indoor fitness bike or rowing machine and avoiding sugar/starch.

Fasting without fat adapted is difficult. Body needs to learn to use fat as fuel. Maybe a keto diet before fasting would have been useful.

Do you have any personal data on lean muscle loss? What Dr. Phinney of 'Low Carb Performance Fame' said that you are losing ~0.25lb/day of lean muscle mass. That is pretty catastrophic in my opinion.

From n=1 experience, if you exercise while water fasting you hardly lose any muscle, but if you don't, you lose a lot of muscle and quite quickly. (Which makes sense - maintaining muscles costs both energy and protein - if you have no intake and they are not in use, why spend that?)

In your personal experience, if you exercise when you are waterfasting, you maintain muscle. That is pretty cool, can you share your exercise routine? The parent commenter noted that exercising while fasting might be painful and I would appreciate hearing what you do. Thanks!

Mostly running at a leisurely pace - most people use many of their muscles when they run - I was doing 5km three times a week. Additionally, I was doing 2x1hr a week of karate practice (a whole body workout), And the occasional random set of 20 pushups / 20 sit-ups / 20 squats, probably 2-3 times a day.

I should note that anything aerobic like running was easy, anything anaerobic (like karate sparring) was not, but it wasn’t painful either.

I did pay attention to electrolytes - especially magnesium and potasssiun - I got cramps when water fasting and not supplementing.

I know my body well, and I think that’s essential to be able to continue - e.g. to know it is magnesium that’s needed now, and not (as one might think) the body is eating itself.

Don’t know how to learn that skill though.

Thank you, that is helpful. Good luck and keep going and keep sharing. We all need to get with it and take responsibility of our own health.

I've read various takes, some say that if you don't eat anything at all, then you lose 100-150g of muscles each week, but if you eat just a little, the muscle loss is considerable.

In your experience, no exercise, no eating ==> no muscle loss?

I tried to do a lighter version of HIIT which got progressively more difficult each day as I read it could prevent loss of muscles and was short enough to finish it with the reserves that built overnight.

Alternate day fasting (Fasting for 36 hours, Eat 12 hours, Fast 36, Eat 12, etc..) has worked well for me and isn't quite as scary.

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