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Chai Jia Xun
Chai Jia Xun

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4 Day Water Fast Experiment

Since coming back to the glorious food paradise that is Singapore, I have been inhaling food non-stop, and as a result have gained 5kg. On one hand, I could exercise and diet and do all that good stuff to try and lose the weight, on the other hand, I could take it to the extreme and simply stop eating for a whole week. I chose the latter.

4 Day Water Fast Experiment

Fasting for a week was not simply a ploy to lose weight (though that was definitely a plus point). I had watched a youtube video that talked about fasting, and how if done correctly, would not be *too* detrimental. The thing that stood out to me most was the claim that after about 3 days of not eating, you stop feeling hunger pangs. That was pretty hard to believe, and I had to try it for myself. Losing weight, and saving money would merely be happy side effects. Granted I could also get terribly sick and die, but that’s a risk I was willing to take. For science.

This is an account of how I did it and how it affected me.

Pre planning?

I watched a single YouTube video. That’s all the actual research I intended on doing.

I also mentally prepared myself, and tried to make my environment more conducive for fasting. To achieve this, I had to stop thinking about food entirely. That meant that I could not have any plans with friends, and work my schedule such that I avoided food entirely if possible. That way I would not be tempted by food and hopefully completely forget about it. That was my theory anyway.

The plan was to do a 3 to 5 day fast. The first 3 days was to see how the hunger pangs affected me, and if I really couldn’t take it anymore, I would eat on the fourth day. But if everything went well and I truly stopped needing food, then I would carry on for another 2 days.


No calories at all. Meaning that only water and unsweetened tea would be allowed. Any supplements would be a pill with only the necessary ingredients and not a sugary vitamin candy.


Day -1 (Sunday)

I still ate as per normal. In fact, I had a buffet the night before my fast. It made me feel so sick of food that I did not have much issue avoiding food the following day.

In hindsight eating a buffet before fasting is a terrible idea. But also I had already planned that meeting a while ago and didn’t want to cancel it.

Day 1 (Monday)

I brought 2 huge bottles of ice cold water to work with me. If I drank a lot of water, I wouldn't be hungry. At least that's what my mum kept telling me as a kid when I kept snacking and she was too lazy to prepare food for me.

I told my colleagues and friends about this so that they wouldn’t ask me to go to lunch and hopefully avoid doing foodish things around me.

That day, I ended up staying in the office till 11pm so that I would avoid being around my family eating.

I was feeling slightly grumpy at the end of the day. On the bright side, I did not feel hungry overall since I avoided food entirely. Food directly contributes to my happiness though, and not having any was a bit irritating. At the very least, I know that I would be able to do a 1 day on 1 day off intermittent fasting thing if I wanted to.

I ended off the day with a Ring Fit session to ensure I keep my metabolism up.

Day 2 (Tuesday)

I woke up pretty hungry. I don’t typically have breakfast, and I very rarely wake up wanting to eat, but today was different. My stomach was complaining from the moment I woke up. I mostly ignored it and carried on with my work day. I felt hungry again at about 1pm and 7pm, which is just around my lunch and dinner times.

I also felt pretty sleepy in the middle of the day so I took a nap. I wasn't sure if it was due to the lack of food, or my usual lack of sleep.

Today was also a day I discovered I needed more nutrients than just water to survive. As it turns out, you need sodium, magnesium, and potassium to function. This should have probably been discovered during the research phase, but eh. I took some sea salt, and a random pill supplement that I found that happened to say magnesium in it.

The level of hunger I felt throughout the day was still bearable. I spent most of the day trying to convince my brain that I don’t need food in an attempt to trick my body into not making me feel hungry.

My mood was still not great. I also started to notice food everywhere. There were ads, pictures or just mentions of food all over the place. Even my bank home page had a picture of a burger on it. The best part is that the picture is no longer there. It’s like they timed it to coincide with my fast.

Day 3 (Wednesday)

I needed to attend a metalworking workshop and though I felt fine enough to drive, to be on the safe side I decided not to. Instead I had my brother drive me. I was alert enough to operate machinery during the workshop without any issue.

After getting home I did crash for a couple of hours. Then I started doing work. While I felt alert enough to do work without much hindrance, I did feel sleepy throughout the day. At this point I was pretty sure it was due to the lack of food. I really just wanted to crawl into bed and sleep the week away.

I willed myself to go for a run that night. It felt like shit. I usually run 5km without feeling too bad, but this time I only did 2.5 and felt way worse than usual. I'm guessing if I were to do a 2 week fast and my body were to get used to the lack of food, this would be better.

Day 4 (Thursday)

Today was the day that I was supposed to forget that hunger is a thing. True enough, it happened somewhat. I did not really feel hungry throughout and didn't really have many food cravings. In fact for most of the day I felt bloated after drinking a little bit of water. I did have a dull stomach ache throughout the day though.

Also I could not stop sneezing throughout the day. Is this the keto flu that people speak of? According to the Internet that's not the case, keto flu is headaches and lerthagy. Maybe I caught covid. (I didn't. I was just having weird allergies, or it could be the lack of food).

Other than the constant dull stomach ache and general mood debuff I felt fine and was able to do work throughout the day. I did take a 3 hour nap in the evening before getting up and continuing my work.

Day 5 (Friday)

I decided to have dinner today. This was mainly because I had a buffet reservation for Saturday night and wanted to make sure I ease myself into eating food again. I did not want to go for a large meal after not having eaten in a week and then throw everything up. In the end, I succeeded in completing a 4.5 day fast.

I had a light dinner. It did not taste as heavenly as I expected from not having eaten for a week. It felt like a perfectly normal meal, with the exception of the dull stomach ache I had been having for the past days. The only ill effect noticed was that my stomach could no longer take spicy foods. A chilli that I could typically consume without issue caused my stomach to burn.

The aftermath:

Right before I broke my fast on Friday. I checked my weight, and I had lost a total of 4kg. While this sounds impressive (1kg per day) it does not take into account the food that I would have to put back into my system.

Over the weekend, after a normal eating cycle, I ended up putting back on 2kg. So overall, I had a net loss of 2kg.

I maintained this weight loss for a couple more weeks, confirming that I did indeed lose 2kg in body mass and not just from not having food. Unfortunately, the land of the food beckoned and I ended up putting the weight back on after a month by consuming a daily bubble tea.

Side effects:

I don’t know if this was caused directly by the fasting, but it happened on the Sunday after the fast. I woke up with an extremely sharp pain in my neck and was unable to cough, sneeze, laugh, walk, turn my head, or generally function as a human for a whole week without agonising pain in my neck. I ended up getting a neck brace to keep my head in place so I could at least work. I suspect it could be potassium deficiency, or it could just be me getting really old.

I also felt terribly sleepy and unmotivated throughout the week. During work I could not do tasks that required too much thinking and planning. While I tried to do other things to keep my mind off food, I found it hard to concentrate on the task at hand.


Water fasting is completely doable if you have the moral support of your peers and have the correct mindset. In my case, my mum kept trying to feed me food and the only thing that kept me going was pure spite.

One thing I noticed is that a lot of social gatherings, if not all of them, revolve around food. Short of having some unbreakable willpower, this also means that you will no longer be able to attend any social events. (Not that you should, what with covid happening anyway.)

You still need some minerals, namely, sodium, potassium, magnesium. (Citation needed, that’s what I got from a few internet articles).

Drinking salt water is not enough, and is also pretty disgusting.

The upside is that not having to deal with anything food related meant that I did end up having more time to be productive or do other things. This was cancelled out by the naps I had to take and me generally being out of it. I suppose I was only very sleepy because my body wasn't used to having no food. I suspect that if I kept this up for more time, I would eventually adapt to it. But that is an experiment for when I go back to the US and am no longer surrounded by all the temptations.


Fasting is not simply halting food intake. You need to prepare actual minerals and keep up exercise so you don't wither away. The health benefits it provides is questionable but at least I got to write a blog post about it. I would probably do this again when I go back to US, a place where I have expressly stated my dislike for the food there. Not liking the food helps a lot in controlling my desire to consume food. Maybe I can finally lose weight permanently this time.

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