A Quick Guide To Fasting
When it comes to nutrition, there are three levers you can pull to practice mindfulness around food and stay healthy: amount, quality and timing.
"Everyone should be pulling at least one lever all the time, two regularly, and all three occasionally." - Dr Peter Attia
The first one means managing the amount of food based on our current needs, either increasing your intake, keeping it the same or decreasing it. The second one gravitates towards a variety of good quality whole foods that are locally produced and have been through minimal processing. The third lever is the topic of this article. Not only what you eat and how much, but when you eat plays a big role in your long-term health.
There are numerous ways to manage your calorie intake. Let’s have a look at a few options. None of these includes counting calories (except for one) and even that one can be estimated rather than precisely calculated.
Overnight calorie restriction
Your typical no-calorie window between dinner and breakfast (i.e. from 7 pm to 7 am). That’s your starting point. If you have to get up in the middle of the night to get a snack, that’s a big problem. The body absolutely needs a respite from digesting food when sleeping. Even feeding deep into the night and just before sleep has proven to be harmful.
80% of your genes are on the 24-hour cycle called the circadian rhythm. When this cycle is disrupted by light at night or by eating it leads to genes not being expressed at the right time which leads to all sorts of malfunctions and diseases.
Studies on mice and humans have shown that one of the first organs to suffer when feeding at any time during the 24-hour cycle is the liver. This damage was reversed and liver health even improved in some cases when individuals practised time-restricted feeding, especially when they were eating in the most active time of the day rather than at night.
One of the reasons this happens is that many pro-inflammatory markers are activated when we have to digest food. This can take from two to five hours after we ate a meal, depending on the type of food. These markers are not inherently bad, they are there for a reason, but ideally, they would become reduced at some point rather than active for most of the day.
Time-restricted eating (TRE)
This is probably the most popular, efficient and sustainable way to manage your calorie intake. It is also highly adjustable to the individual's preferences and abilities.
You would increase the overnight ‘fast’ to a slightly longer window and make that a daily habit. For example, if you sleep from 10 pm to 6 am, having dinner at 7 pm and delaying breakfast until 11 pm would make it a 16-hour fast or the so-called 16/8 fast. So when someone says they’re skipping lunch, that’s not very helpful. Rather skip breakfast or dinner. Remember you are already fasting during sleep, so just add to that period from either side.
The feeding window usually suggests ad libitum food consumption meaning as much as you want. You only focus on when you eat rather than what and how much. Of course, for health reasons you want to avoid overeating.
The 8-hour feeding window has been shown to have all the positive effects of lower inflammation, weight loss, better body composition, better insulin sensitivity, blood pressure, etc. Even people that ate complete junk have shown improvements! Most importantly, this protocol has the highest adherence among individuals, which means people are able to stick to it in the long term.
If you are new to this, make sure to start slow. Have your breakfast an hour later or dinner an hour earlier and slowly expand from there. I strongly feel that any individual would benefit from simply avoiding calories two hours before and after bedtime. Anything more has to be adjusted to individual variations. We all have different pain thresholds, emotional cues and memories linked to food, microbiome, hormones, health conditions, lifestyles, preferences, etc.
If at some point you feel you can’t make it until feeding time, to make things a bit easier, you can have some healthy fats (handful of nuts, a teaspoon of butter in your coffee or tea, a bit of avocado, etc.). Make sure you drink enough water throughout the day. You can also drink tea or coffee in the fasting window as long as they don’t contain milk or sugar.
It takes the body a few weeks to get used to this new state and the process that happens in the liver is called gluconeogenesis - the generation of new glucose. After week three the liver has learned to not rely on outside sources of glucose and it keeps generating it itself at a steady pace. This is really important not only because it’s what keeps you away from crashes of hunger but it is extremely healthy to have even glucose levels in the blood for optimal cellular performance.
Alternate-day fasting (ADF)
This is when your caloric intake is anything but ad libitum every other day. Technically, the ideal way to do it would be to consume nothing on those days, but it is quite challenging in the long run. More commonly people would have hypocaloric days every other day, meaning they would for example consume only 500 or 1000 calories and have no restrictions on the other day.
A similar variation would be a 5:2 fast, where you would eat normally five days a week and select two non-successive days for a hypocaloric diet of 400-600 calories. Fasting Mimicking Diet (FMD) is a brand name that describes the same ADF protocol but by consuming their pre-packaged product 5 days a week.
Intermittent fasting (IF)
This term became widely popular to describe the above-mentioned TRE. Since a 16-hour fast doesn’t technically fit the description of a fast, because all the fasting mechanisms don’t get a chance to be fully activated, this term rather describes a 24-hour fast in some regular frequency, let’s say once a week.
After more than 18 hours of fasting autophagy (explained below) starts to kick in more efficiently while many other factors that affect the slowdown of ageing also kick into a higher gear.
Periodic or prolonged fasting (multi-day)
A true prolonged fast is done by only consuming water (plain or bubbly) and minerals for three to seven consecutive days.
Some tea is also accepted. Many people argue that black coffee also helps with autophagy but the research is not conclusive on that. However, if you are caffeine dependent it is not recommended to stop coffee consumption since fasting is challenging enough on its own. The difference is not as huge as some purists portray it to be. Having said that, if your aim is to give your gut some rest, then you definitely want to avoid coffee consumption as well. Caffeine is not so much the issue as some other phytochemicals in coffee, that is why tea is acceptable.
According to Dr Peter Attia, three days is probably the minimum to hit some of the physiologic benchmarks of fasting such as glycogen depletion, significant reduction of glucose and insulin that triggers autophagy and the inhibition of senescent cells, inhibition of mTOR and activation of AMPK. Please check our last week’s article to refresh your memory on what these processes are.
After the three-day mark, the autophagy almost kicks into a higher gear or so-called chaperone-mediated autophagy or the deep cleanse.
Humans can endure incredibly long periods without food, approximately 60 days. However, the conditions can drastically affect that. It is one thing to fast in a lab and something else to be stranded without food in a desert.
Dr Alan Goldhamer is the founder of True North Health Center where they regularly take patients through medically supervised 40-day water-only fasts. The results are incredibly transformative, but any fast longer than 72 hours needs some level of knowledge, and fasts longer than 7 days should be done with some medical supervision.
Autophagy
Many important pathways that take care of the DNA repair and stabilisation of the epigenome are triggered when you are exposed to occasional prolonged periods without food. Autophagy is one of them. It is a process of recycling old and dysfunctional proteins to prevent them from accumulating in tissues and causing disease.
In many ways giving your body some rest from food will not only keep it metabolically flexible (being better able to utilise the energy stored as fat and glycogen) but will also give it time for a good cleanup. It’s like a clerk that is getting swamped by constantly arriving tasks. She is only able to attend to the most urgent ones at any given time, leaving the less important ones to pile up endlessly in the corner. Eventually, her system would collapse.
Conclusion
Building your own perfect fasting practice will highly depend on your non-negotiables in life, but let’s start with this: avoid food for at least 60 minutes after waking, ideally 120 minutes.
Additionally, you want to avoid ingesting calories (even 1 gram of sugar will break your fast) two to three hours before bedtime. This assumes that you spend 8 hours in bed. Sleep-related fasting is extremely important due to the cellular repair processes that occur in the liver, gut, microbiome, brain, etc. and has a strong effect on your circadian clock.
Based on the literature, an eight-hour feeding window seems to be the best for the majority of people, says researcher and professor Dr Satchin Panda. Regular placement of the feeding window within 24 hours is also important, although you don’t have to be too rigorous about it. You just don’t want it to shift two hours left and right every day.
Even if you are fanatical about fasting and take periods of extended hunger very well, you don’t want to practice multi-day fasts too often or for too long and cause other damage including muscle loss, micronutrient deficiencies and hormonal imbalances.
I personally found that a daily 16-hour fast, a weekly 24-hour fast and a three-day fast every six months works best for me. I wish to encourage you to be your own researcher and experiment with what works best for you. Make sure to always consult your healthcare specialist if you have any concerns.
Lastly, never forget how important refeeding is. Meals should be enjoyed in a stress-free and distraction-free zone. Make sure you fuel your cells with high-quality energy in the amounts needed for your health goals.
Ask yourself how you can better manage your health by pulling one of the three levers constantly, two on a regular basis and all three every now and then.
Resources and further reading & listening:
https://www.youtube.com/watch?v=9tRohh0gErM&t=1211s
https://www.foundmyfitness.com/topics/fasting
https://www.foundmyfitness.com/episodes/valter-longo