My experience with a 7 day fast

Many people are adding some form of fasting as a daily, weekly, monthly or annual practice these days. It’s nothing new – people have been intentionally fasting for thousands of years whether for health or religious reasons. What is new is our understanding of the physiology behind fasting. However; information on the experience and practice of fasting is being lost or less emphasised amongst all the latest research. So I want to share here my experience with my first one week fast. No food for one week – I just had water, herbal teas, black coffee and black tea. Let’s see how it went…

But first, what is fasting?

Simply put, fasting is any time you’re not eating. Between lunch and dinner – that might be a few hours fast. Some people say it’s from the time of the last digested meal so they won’t consider between lunch and dinner a fast. Practically everyone starts counting a fast from the moment they stop eating, so don’t get caught up in the small details for now. Between dinner and your next meal, usually, 8-10 hours later is your break-fast. It’s a break from eating but let’s be clear about what it is not – it is not starvation.

My scan (explained below) showed that my body was holding around 19kg of fat. That’s around 170,000 calories or 77 days worth of energy! I’ll never go down to 0% fat, but it shows I have enough in my calorie bank to fuel me for close to a couple of months before I go into complete energy bankruptcy and get evicted from my body (I die!). Starving is when you get down to a dangerously low level of body fat stores and/or deplete your vitamin stores leading to malnutrition. A one week fast will certainly access my energy stores but it’d take many weeks more before I reach levels that would be considered starvation.

Fasting comes in many forms but I chose to do a 7 day fast with no food at all. Just water, herbal teas, and black tea or coffee.

Why 7 days?

People choose to fast for many reasons – weight loss, general health, anti-ageing, spiritual or religious reasons. My motivation was to experience the healing benefits of fasting.

As you get older you may notice some things don’t work as well as they use to. Your digestion might not be so good, you make wake up feeling inflamed or achy. Your recovery from exercise takes longer or injuries seem to linger for longer. There’s plenty of evidence now that fasting can help restore or improve these things by giving your body a cellular spring clean through a process called autophagy. This is where your body has used up the proteins and nutritional building blocks of your last meals, so your body has to break down cells and cellular spare parts/waste to make new cells. It doesn’t have anywhere else to get the cell building material from, other than to break down existing cells. The body does this in a smart way and recycles cells that aren’t functioning as well as they should be, and uses the parts to build new cells. In some cases, the body may even break down pre-cancerous or early-stage cancerous cells preventing the development further.

Autophagy kicks in after a couple of days but really ramps up from day 3-4 onwards. There are numerous other benefits I wanted to experience such as simply giving my digestive system a rest, burning ketones for fuel which is supposed to give heightened clarity, and generally let my body have a full rest and do a little internal spring cleaning.

How I prepared

I don’t think anyone should jump straight into a 7 day fast without any preparation. In the past, I’ve spent extended periods using intermittent fasting. For several months leading up to my 7 day fast, I practised 18, 24, 36 and 40+ hour fasts. This gradually gets your body used to the experience and reduces your anxiety about not eating. Before fasting, many people think those hunger pangs and grumbles you feel on a normal day will progressively get worse through the fast. Once you start practising with short fasts you’ll understand that’s not the case. You may get a little stomach rumble but it’ll quickly go away if you have some water or tea.

For an extended fast over a few days, particularly in a humid climate like in Hong Kong’s summer, it’s wise to have some electrolytes. If you don’t get the electrolyte balance correct before the fast you may end up having the wrong amounts and find yourself needing to run to the bathroom and making your fast a very uncomfortable experience! I simply used powdered magnesium and potassium diluted in water spread throughout the day. Try this for a week or two before to make sure you are comfortable with the amount.

What can I drink?

I chose to still consume black coffee, black tea, herbal teas and obviously water. I didn’t want to make the fast any more uncomfortable than it needed to be and there are beneficial polyphenols in teas that can support our gut bacteria. The teas I chose were ginger, stinging nettle and hibiscus. These have powerful anti-inflammatory compounds that would further help the healing effects of the fast.

The only other additions I made to my fluids were magnesium, potassium and later sodium. You can use electrolyte mixes, and there are some fasting salts you can get that are purposely for fasting but I just chose to mix my own from pure powders. I drank as much of the herbal teas as I wanted but made sure I had about 400mg of Magnesium and 2g potassium diluted in 2litres of filtered water per day.

Brief summary of how I felt through the fast:

Day 1-2

I started my fast after finishing lunch at one of my favourite vegan spots. I chose to start my fast in the afternoon with the thinking that when it comes to breaking my fast a week later I could spend that afternoon eating small quantities gradually and then eat more the next day. It’s also less of a mental slog knowing I can break my fast mid-afternoon vs late in the evening. Each to their own, you can choose a time that suits you best.

Day 3

This was the only time I was really feeling a little rough with energy. It was the time that my body really switched to using ketones. I’m not someone who follows the keto diet or regularly goes into ketosis so I’m not sure if I felt this any more or less than people that are more adapted to this phase. That said, it wasn’t terrible. I just noticed I was feeling a bit more off energy-wise. I also noticed a little light headedness which improved when I added some Himalayan pink salt to my water and tea.

Most days I managed some very light easy yoga and meditation sessions. I still felt fine going to the flower market to pick up some soil and plants. Sorting out my rooftop garden was my main project during this fast. I’d recommend you have at least one project to keep you occupied during the fast. Nothing too strenuous but still enough to keep you mentally or physically busy.

Day 4-6

Pretty plain sailing here. The main side effect I had was freezing cold feet! This started from day 2 and pretty much stayed through until the end. It was the peak of Hong Kongs hot and humid summer yet I felt the need to wear woolly socks!

While I didn’t really have any hunger pangs, I was looking after some friends cats and their food was starting to smell delicious!


Energy-wise I felt great. On day 6 I even went for a little hike and did some handstands and acroyoga. Strength felt good but walking up the hill was a little challenging mainly with the feeling of lightheadedness. It wasn’t anything dramatic, I just knew to take it easy.

Day 7

This was probably the worst mentally, knowing that I was approaching the last hours of my fast. The last 12 hours were horrible – I should have kept myself busy with something but I was watching the clock the whole time. My body wouldn’t care if I made it 6 days and 23 hours but I was determined to make it a full 7 days.

How I broke my fast:

I wanted to break my fast gradually. I think that’s a sensible thing for everyone to do after a fast over 3 days or more. I chose to make some apple and Chinese barley tea. Just stewed the two together and sipped on it. It was warm, comforting and came with a little fibre and fruit sugars to gradually get my body out of ketosis and get the body digesting again.

I sipped on that over a few hours then ate/drank a homemade vegan pho. It was delicious even though it was simple and fairly plain. It just contained a few solids to digest like rice noodles, tofu and herbs. The broth was comforting.


A few hours later I had a small bowl of oatmeal and some of the leftover stewed apple and barely.

Doing it this way felt like the perfect break to the fast and I think I’ll pretty much do the same next time I fast for an extended period.

Before and After results

I wanted to record as much as I reasonably could for this fast. I did a DXA scan (to measure body fat, muscle mass and bone mass) at the start, at the end and 3 weeks after the fast. I also measured cholesterol at the same time. During the fast, I measured my weight, ketones, urine pH, blood glucose, and for those interested – my bowel movements.

I didn’t have any expectations about the changes in cholesterol during a 7 day fast. That said I was quite surprised to see such a big jump in LDL cholesterol yet triglycerides and HDL remained pretty much the same at the end of the fast. However, nearly 3 weeks post fast and eating normally I can see my LDL is starting to go back down and my HDL has improved.

The reasons for these changes go deeper than I first thought. It’s not as simple as using more fat stores so your cholesterol goes up. LDL has an effect on cell signalling to initiate cell repair and recycling, and HDL has an influence on inflammation. It’s something I’m only scratching the surface on so I won’t comment too much here. What my personal experiment here seems to confirm is what previous studies have shown – during a 7 day fast your cholesterol goes up (particularly LDL) and afterwards, it should return to baseline or improve.

So I lost a lot of weight initially during the fast. No surprise – I didn’t eat for a week! While I lost 1.35 kgs. of fat, I initially lost over 5kgs of lean mass! 3 weeks later I put on close to 4kgs back to my total lean mass. There’s no way I would have put on 4kg of muscle in that time so most of it would be water weight, mainly stored in the muscle.

I think having a few weeks follow up scan is a good way of measuring net effects of the fast in normal day to day life after a period of time, rather than just seeing the short term effects. My net fat loss 3 weeks later compared to before the fast was 1kg. My net lean mass loss was about 1.3kg. I had lost weight, I had lost fat, but I had lost lean mass the most. Some people doing extended fasts and finding themselves on this weight loss and weight gain rebound pattern should take note of this. I personally don’t think an extended fast is the best way to lose weight. For me, all the other benefits I gained, made worth losing some muscle mass so I would recommend extended fasts for those reasons, namely – gut healing, overall healing and anti-inflammation.



In addition to the DXA scan and cholesterol test, I tried measuring a few things myself to have some data during the fast to see what happens and when. A few things here aren’t too surprising – glucose goes down, ketones go up and my body switches energy sources. A couple of things were interesting to me – as my blood glucose went down and my ketones went up, my resting heart rate also went up. After I broke the fast my heart rate seemed to be back on a downward trend again. I haven’t looked into this more, for now, it’s just an interesting note that I might come back to.

The second interesting note; interesting for me and apparently quite a lot of people interested in my week-long fast, was the frequency of bowel movements. I pooped on day 1 (no surprise) but then again on day 4 and day 6. There you go, I hope you’re glad you asked.

Final thoughts:

I’m writing this a month after finishing that week-long fast and I want to do it again! That feeling alone is enough to know it was worthwhile.

From the results here I wouldn’t use it as a weight-loss tool. Although I lost some fat, there was plenty of muscle that went with it, even accounting for the muscle that came back (water and glucose weight) after a few weeks. What I would use it for is for a metabolic holiday and spring clean. I felt rested, somewhat healed and recovered in a way I haven’t experienced before, Inflammation in my joints calmed down, my digestion improved and there was a real feeling of clarity and overall wellbeing. Not to mention the satisfaction of detaching yourself from the addiction of eating and knowing your mind is strong enough to overcome cravings.

Jumping into a one week fast with no preparation is a bad idea for most people. See a doctor beforehand if you have any medical conditions. Practice gradually with some intermittent fasts, then one and two-day fasts. Enjoy them!

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