4-Day Water-Only Fast – Key Benefits and My Experience

The following are the currently known key benefits of a water-only fast which needs to be done for at least 3 days:

1. Improves immune function
2. Autophagy – repairs damaged cells and removes dysfunctional cells (also known as zombie cells) that can lead to disease
3. Reduces both neuro and musculoskeletal inflammation
4. Decrease autoimmune disease
5. Benefits gut flora
6. Increases DNA repair

Apart from the priceless value behind these benefits, I also took on this fast as a challenge to further explore my physical and mental limits and to free myself from any immediate dependencies on 2 of my favourite things in life, that is food and coffee, which while I still handle with care as part of my weekly routine, provide me with great pleasure. Moreover, to kill as many birds as possible with one stone, I also chose to schedule my fast for the Holy Week as an exercise in spiritual rekindling.

Building up for the 4-day fast

For context, until a month ago my longest fast was around 16 hours which I had only tried a couple of times, mostly by chance rather than deliberately. Therefore, the idea of doing a 96-hour fast was initially scary to say the least.

After digging deeper into the topic and speaking to a few people whom I know fast on a regular basis, I decided to start building up for it over 3 weeks. In the process I first extended my longest fast to 24 hours (2 weeks prior to the 96-hour fast) and then the following week to 38 hours. During these trial fasts, I still performed my gym workouts with no noticeable changes in strength. (Note: as counterproductive as it may seem at face value, it is the act of continuing to lift weights that minimizes the risk of muscle loss during a fast).

I felt that I faired pretty well through these trial fasts which helped me build confidence in preparation for the 4-day fast. The only issue I experienced during the 38-hour fast was a mild headache that kicked in during the first afternoon and stretched to the evening before gradually subsiding by the next morning. I associated that headache with coffee withdrawals rather than the lack of food itself.

In the days leading to my fast, I deliberately informed more people about my challenge, essentially forcing myself beyond a point of no return. I felt that by doing so I was elevating the level of accountability not only to myself but also to the people I told. I tend to use this technique in whichever challenge I set myself against as I find it boosts willpower and increases my odds of success.

The actual 4-day fast

I started my 4-day fast on Monday night at midnight and finished it on Friday night at midnight. In the process, I tried to keep the same routine that I usually follow.

During days 1, 2 and 3 I kept my mind busy with work, sitting most of the day at my laptop. Day 4 was a day off from work given it was Good Friday.

When the usual lunchtime arrived, I still left my laptop but instead of going to the kitchen, I went out for short walks.

I performed my usual gym workouts in the evenings of day 1, day 2 and day 3. On day 4 I rested from the gym but walked 10k steps.

I drank 4 litres of water (filtered through reverse osmosis) a day (including the water during my workouts) and had a teaspoon of pink salt a day, split between half a teaspoon with a glass in the morning and another half with a glass an hour before my workout. This is the water I drink on a daily basis. I also kept taking 250mg of magnesium at bedtime. Both sodium and magnesium are essential nutrients, meaning your body can’t make them on its own. They help maintain fluid balance, maintain a normal heartbeat, regulate nerve and muscle function and fight dizziness, headaches and fatigue, all of which are key body functions that may become particularly challenged during a water-only fast.

I also chose not to drink any teas, coffees or flavoured water as I wanted to go with an all-in attitude and also to avoid any ill side-effect that these might have on the key benefits mentioned above.

I had my usual bowel movement on day 1 but nothing on Day 2, 3 and 4. I didn’t feel constipated throughout. Bowel movement returned the day after I broke my fast.

On day 1 my morning weight was 73.1kg. On day 2 it was 72.2kg, day 3 – 71.7kg, day 4 – 71.3kg, day 5 – 70.8kg. The drop after 1 day of fasting was 0.9kg whereas on the following days I dropped an average of 0.5kg per day, for a total of 2.3kg. Prior to the fast, I was actually concerned about the weight drop and muscle loss, however in the end it wasn’t bad at all. Clearly, the first day saw a bigger drop in body weight than the following days given the emptying of the gut from the prior day’s food and the related reduction in water from the body.

Another concern I had prior to the fast was how it would affect my sleep. However, the irony was that during the 4 days, I figured that bedtime was actually something I was looking forward to as it allowed for a quicker passage of time. Sleep quality was generally good and my resting heart rate was steady throughout at an average of 41.

The following is a recap of how I felt through the 4 days:

DAY 1: started feeling pretty hungry in the afternoon which continued through the evening. The fact that I knew I could only eat again in 3 days didn’t help. Every time I thought of food I tried to shift my thoughts to something else. I also felt very sleepy late afternoon so I ended up taking a nap before the gym, something which I never usually do. I also felt rather cold during the day. On a positive note, I didn’t experience any headaches.

DAY 2:  started experiencing brain fog and fatigue in the morning which lasted until late afternoon. Early evening I started to feel alert again. Didn’t get the same urge to nap as the previous day. I continued feeling cold during the day. No headaches on day 2 either. If I had to choose between food and coffee, I was definitely missing food more than coffee.

DAY 3: this day was interesting. Brain fog and fatigue experienced during day 2 were gone, rather I felt pretty energetic and productive all through the day. This is consistent with what Chris Hemsworth experienced in terms of timing and likely indicates that in the absence of glucose from food, my body started using ‘ketones’ by burning body fat for energy. Ketones are known to sharpen mental focus and heighten senses and perception, which pretty much chimes with the way I was feeling during this day. Another interesting observation is that I did not feel hungry during day 3.

DAY 4: it goes without saying that I woke up particularly excited having managed to pull through that far in the fast. Given it was the last day my discipline threshold was particularly high, which came in handy when I was surrounded by people enjoying traditional Easter delicacies as I was going about my Good Friday rituals. While I continued to feel cold, what was more annoying was that my mouth felt constantly dry even if I was drinking regularly. This is a common side effect of fasting. When the body isn’t taking any food it stops producing saliva. Interestingly, saliva actually helps to clean the mouth of bacteria which is why the body produces it when eating. On a good note, I didn’t feel hungry during the last day except for the last hour when I literally started counting the minutes to my first food after 96 hours.