Prolonged Fasting Benefits (48-120 Hours Without Food)
Intermittent fasting is all the rage right now. Usually people only fast for 16 hours and sometimes 20 hours. Prolonged fasting (which is fasting for over 48 hours) is increasingly becoming recognised as a potential way to extend your life, prevent cancer and lower inflammation.
The Benefits Of Prolonged Fasting
I recently did my own 3-day prolonged fast and it was an awesome experience. Today I’m going to share the reasons why I did it.
You’ve probably heard of intermittent fasting before. Fasting on a regular basis provides you with a wide variety of benefits ranging from increased insulin sensitivity, potential weight loss and even increased cognitive function.
There are also some unique benefits which occur after we fast for longer periods of time (48 hours+) and that is exactly what I’m talking about today.
The first and most obvious benefit is the effect nor eating has on your weight. You’ll lose weight quickly for multiple reasons.
Firstly, you’re going to lose weight because you’re losing a lot of water. Your body depletes glycogen stores in the liver first, then from the muscles.
After these stores are depleted, muscle glycogen is depleted. The depletion of muscle glycogen comes with a cost of a substantial amount of water loss.
This is why you’ll often hear that it is important to increase your water and salt intake when in ketosis.
After your body uses what glycogen was available it will begin to burn fat for fuel or more specifically tone bodies. This entails a metabolic state of ketosis achieved either through fasting or nutritional ketosis (by following a ketogenic diet).
You essentially become a fat burning machine.
Because you don’t have any dietary fat – as you would on a ketogenic diet – your body begins to eat its own fat stores and hence why not eating is obviously effective for weight loss.
But most people will just gain this weight back. I suggest that you don’t make prolonged fasting your main method of weight loss. It’s simply not sustainable.
When you stay in a state of fasting ketosis for a prolonged period of time something called autophagy occurs. Autophagy roughly translates from Greek into “self-eating”.
Your body begins to eat itself. Sounds scary I know. Autophagy recycles waste from the body and repairs any oxidative stress (1).
Autophagy has anti-ageing properties and is also very important for muscular hypertrophy (growth).
Long-term fasting is also being considered as a potential therapeutic therapy for cancer patients. There’s a lot of research about how prolonged fasts could potentially prevent certain cancers (2). The same goes for ketogenic diets as cancer cells feed off glucose.
A prolonged fast is generally considered anything over 48 hours and isn’t usually practised for over 120 hours, although longer fasts are not unheard of.
Some of the most profound benefits of prolonged fasting are likely due to the significant depletion of glycogen in the body.
Generally, humans can survive 30 days or so without food and a few days without water.
The length which someone can survive without food depends entirely on that individual. Someone with more body fat can clearly survive longer than an athlete with 6% body fat.
I don’t recommend 30 days. In most cases, this isn’t necessary and unadvisable.
Prolonged fasting also has some benefits for the brain. Think about it logically. If food is scarce, clearly you need to get more of it in order to survive.
Therefore your requirement to think critically will increase so you can strategise ways to gather and hunt for more food.
I’ve written about how ketosis may be advantageous for the brain here if you’re interested in learning more about this idea.
Prolonged fasting and fasting, in general, has been shown to lead to more brain-derived neurotrophic factor or BDNF for the brain. BDNF is like fertiliser for new neurons (3).
Synaptic plasticity improves and you also become more resilient to stress.
Each time you fast for a prolonged period of time, the reduction of white blood cells increases stem cell revival.
With the depletion of white blood cells, an enzyme called PKA is reduced which allows stem cells to begin to rebuild the immune system (4).
This is important because, for those suffering from a compromised immune system due to cancer treatments, fasting becomes a viable option to alleviate some of the issues chemotherapy can cause.
Anecdotally I must say that ever since I’ve started intermittent fasting all those years ago I have rarely been sick. Sickness was something I used to struggle with.
I would get sick very frequently and fasting seemed to alleviate this somehow. Whether it’s causative, I’m unsure, but it’s definitely no coincidence.
Adiponectin is also released from fat cells during prolonged fasting. Adiponectin is an anti-inflammatory agent which helps protect against chronic disease (5).
Fasting in my opinion and others is the perfect Stoic exercise to test your discipline and willpower. It’s also a great way to ‘rehearse poverty’ as an exercise of increasing your gratefulness for what you currently have.
The mental discipline and willpower involved in fasting for a prolonged period of time is empowering.
Today we live in a world of comfort.
Too much comfort is not a good thing.
We need discomfort in our lives and since we aren’t provoked by it throughout the day as we would have been in nature.
The idea that fasting can act as this tool and help aid improve your health is pretty cool.
Negative Consequences Of Fasting
There are a lot of benefits to prolonged fasting and the research is convincing but I have to mention the potential downsides of abstaining from food for so long.
Some common side effects of a prolonged fast include more noradrenaline and cortisol. This is an important reason why fasting is good for weight loss. But too much noradrenaline is not a good thing.
Cortisol (the hormone released in response to stress) is basically an evolutionary survival adaption to survive.
But too much stress is going to cause potential binge eating which is exactly what you don’t want as a result of your prolonged fast.
People can report feeling weakness, dizziness and even nausea when on a longer fast. It’s important to stay hydrated and even include some salt in your water to balance your electrolytes and compensate for the loss of water followed by glycogen depletion.
Fasting for extremely long periods of time (i’m talking over 7 days) can have some major drawbacks if you don’t do things right.
If you begin to catabolise your own protein as you have no glycogen and fat left then protein (which is what your heart is made of) is metabolised for energy.
That doesn’t sound too fun, does it?
This can cause heart failure. This isn’t going to happen if you do a 3-day fast, don’t worry, but if you are underweight, pregnant, have circadian rhythm issues, or have hypoglycemia you shouldn’t even think about this.
If you’re genuinely feeling unwell when you try a prolonged fast then don’t listen to people who tell you your dizziness is a sign of “cleansing” or whatever. Listen to your body, use your common sense and be smart.
Just because you start something doesn’t mean you have to finish it.
If you have an eating disorder you need to be mindful that fasting (despite being healthy in many ways), can transform itself into another way to feed this disorder.
Prolonged Fast Protocol
The reason is that getting into deep ketosis through nutritional changes can take much more time. By getting into ketosis quickly you also prevent as much muscle loss as possible.
Tim recommends combining your fast with MCT oil so that you can utilise ketone bodies for fuel when you’re not producing enough of your own yet.
MCT oil is completely optional, but it’s something I decided to use with great success when I do my prolonged fasts. You can watch my day to day experience of the 3-day fast here:
Technically consuming anything other than water isn’t a “proper”. Anything which requires the use of the stomach triggers insulin to an extent.
A small amount of coconut oil, MCT oil or black coffee is hardly insulinogenic (increases insulin) and shouldn’t prevent many of the benefits (such as autophagy) from occurring.
Coffee (especially decaf) can also be used strategically as a tool to decrease your appetite due to the increase in the peptide hormone PYY (5).
I prefer tea. I recommend drinking green tea during the day and camomile tea before bed.
3 Day Prolonged Fasting Protocol:
• Stop eating between 6-8 pm
• Walk for an hour or two to shift your body into ketosis quicker
• Be sure to hydrate
• Exercise at the gym if you want (nothing too strenuous)
• Increase your water consumption with added salt.
• Consume some coffee and exogenous ketones and MCT oil (optional)
• Walk for an hour or so
• Exercise is optional
• No exercise
• Walking is fine if you’re still not completely in ketosis (you should be)
• Be sure to hydrate and keep your salt consumption high enough
• Coffee and MCT oil as necessary (optional)
• Proceed to break the fast following the guidelines below
Breaking The Fast
It’s important to break a fast correctly. You can usually eat a big meal after fasting for 16, 18 or 20 hours, but once you’re over 48 hours mark you really should take time to consider what you’re eating and how much of it (especially if it’s your first time).
I’ve learned this the hard way.
Refeeding syndrome can occur when you go from ketosis (fat burning) to glucose energy too quickly. The sudden surge of the hormone insulin needed to digest all these new sugars requires a lot of potassium, magnesium, other vitamins (especially vitamin B1).
Refeeding too quickly can lead to sudden death. This isn’t going to happen on a fast over a few days, but if you’re doing an extremely long fast (which I don’t recommend) and you eat far too much food, then the possibility is there.
The longer you fast and the more you eat, then the greater the chances of problems occurring. 3 days isn’t too long, but some people are more sensitive than others.
Start slow people!
Prolonged fasting can be a great way to improve your health, but take should be taken in order to do it right.
Some of the benefits of prolonged fasting include:
• Increase neurogenesis (new brain cells)
• Immune system reset
• Reduced inflammation
• Increased autophagy (recycling or self-eating of the cells)
• Increased willpower, self-control and discipline
Prolonged fasting is not for everyone and you must make sure you’re in good health before you proceed with this more extreme form of fasting.