The truth about fasting: Does the 72-hour water fast really work? We tried it and the results were surprising

 
Harry Thomas

What it would be like if you had no food for three days? No coffee, no juice, no supplements. Just plain old water. Well, let me tell you...


First of all, why on earth would anyone want to do this? Is it even safe?

I’ve been in the fitness industry for over 12 years and during that time my knowledge of – and interest in – nutrition has massively developed. When I was starting out as a Personal Trainer, all I really knew was how to lead a workout; I cringe thinking about some of the techniques I used to use. Years of experience have taught me that nutrition is the most important thing, no matter what your fitness goals.

Nutrition isn’t just about weight loss, either – it affects everything from recovery time to the ability to break bad habits, energy levels to mood, quality of sleep to cognitive ability. We are machines made of flesh and food is the fuel that makes every one of our major systems function. Annoyingly, every person functions differently, so it’s my job – and your job – to work out each individual’s relationship with food.

One approach to nutrition that’s been getting a lot of coverage – and some success – is something called “intermittent fasting”. Everyone has heard of the 5:2 diet (eat normally for five days and fast for two), and you may have heard of the 16:8, for which you don’t eat anything for 16 hours, and then only eat within an 8-hour window. This approach works well for weight loss because you are essentially skipping either your first or last meal of the day, meaning you consume fewer calories. I’ve used this approach myself and seen some great results, which made me more interested in the concept of fasting.


It’s an idea that’s been around for centuries. Many religions and sects have used fasting to help achieve enlightenment or a spiritual connection. Some fast for days or even weeks at a time (the human body can survive around three weeks without food, although once you get to the sharp end you’re going to see some pretty horrendous side effects, so it’s not something anyone should attempt).

I did a lot of reading up on different ways to fast and one method that stood out was the 72-hour water-fast. Clearly not eating for this long means your body will be dipping into its fat reserves, resulting in weight loss. But people claim a range of other benefits, including improvements to your immune system, giving your digestive tract a break, better blood-sugar regulation and reduction in inflammation. Others claim it’s a load of hokum – and it’s certainly a good idea to approach these things with a healthy dose of skepticism.

When fasting our bodies break down stored fat and produce ketones for energy. Ketones burn a lot more efficiently than glucose and, although there’s scant scientific evidence, people claim this helps with mental clarity.

There’s nothing wrong with aggressive weight loss, but low – or in this case zero – calorie diets are certainly not sustainable and should monitored closely. It also goes without saying that there is a difference between a healthy person exploring this type of fasting in order to better understand their body and someone with a propensity towards eating disorders using it as an excuse to forego food; if you think you may be suffering from an eating disorder, you can find advice at beateatingdisorders.org.uk.

The Fast

I love food and eat a lot of it, so the idea of consuming nothing for 72 hours was daunting. Day one was the hardest – by 5pm I had a cracking headache, despite drinking around six litres of water; I think it was at least partially down to caffeine withdrawal (I usually have three strong coffees a day). Someone recommended drinking a mineral-rich salt solution such as Himalayan salt, which replaces the electrolytes flushed out of your body; whether it was a placebo effect or not, the headache soon disappeared.

Throughout the first day, my mind was persistently telling me I was hungry. The second day my stomach was telling me I was hungry by constantly rumbling. By day three, I wasn’t hungry at all. My energy levels stayed surprisingly high throughout the fast and I trained every day. I even completed two workouts on the final day, both at a relatively high intensity and without a noticeable dip in performance.

Habits

It struck me that our attitude towards nutrition is governed as much by habit as by hunger. We drift through much of our life on autopilot, eating when we usually eat. I look forward to picking up breakfast at my local coffee shop, and I was always “hungry” when I got there. But even after a couple of days, I started to realise that my “hunger” was a symptom of routine. Nutrition habits become ingrained and we build up an internal narrative; “I can’t function properly without breakfast”, “I need a coffee to kickstart my day”, “If I skip lunch I get a mid-afternoon lull”.

One of my habits was always visiting the fridge after my dinner to see what I could scavenge; I did it so often it became a learned response, with no particular goal in mind, apart from eating something – this kind of subconscious habit is how people can fall into the trap of overeating.

Mindset

Another thing I noticed is how powerful our thoughts are. On day one, people would ask me how I was feeling. Without thinking I replied, “I’m hungry”. This happened at least four times before I realised that I wasn’t actually hungry, but the act of saying it made it true. I think this is true of a lot of scenarios. How many times have you said you’re tired, hung over, stressed, anxious or bored? If you tell yourself you’re tired, you will be tired. Try flipping those negative responses to something more positive.

The same goes for your fitness goals. After I completed the 72 hours, over 20 people in my network decided to try it out, but very few finished. Most started out saying things like: “I don’t think I can do it” or “it’s going to be really tough”. You can think these feelings into existence. If you’re aiming towards a goal, tell yourself you’re going to complete it. This goes for everything from losing weight, to getting a job, to climbing a mountain.

Fat loss

It wasn’t the reason I started fasting, but the results I achieved were pretty crazy. I lost 3.2kg (6.4lbs), which was mainly fat, and didn’t appear to lose much muscle mass, which was a big surprise. As you can see from the pictures, I look much leaner, and over the following weeks I kept the weight off. Of course, it’s important to pay attention to how much food you eat after fasting, as putting weight back on can happen incredibly quickly.

Overall, the experience was insightful. I noticed a change, both physically and mentally. It’s a fairly extreme thing to do, and as I said, I’d exercise caution. But I walked away with a real sense of achievement. Isn’t for everyone, and there are more sustainable ways of losing weight, but if you’re interested in learning something about your body, I’d give it a go. Perhaps start with 24 hours and see how you get on. If you don’t have any problems, work your way up. And remember: go into it with a positive attitude.

Related articles