How to Fast for 3 Days (3 Day Fast Benefits)

Siim Land

I’m a huge proponent of doing intermittent fasting in some shape or form. This article explains you the 3 Day Fast Benefits and how you can do it without getting hungry. 

72 Hour Fast?!

If you haven’t tried extended fasting before or simply think that it’s crazy, then let me try to demonstrate your immediate reaction. *Ahem* Are you mentally debilitated? To not eat anything for 3 days is just insane! There’s no way I’m going to do this voluntarily.

It’s a natural response indeed. Our society and physicians have conditioned us to think of fasting as dangerous to our health and any feeling of hunger is a sign of starvation. In reality, the opposite is the case because

When in a fasted state, your physiology is in an altered state that empowers and nourishes.

Fitness gurus and medical doctors mostly preach the doctrine of consuming several small meals throughout the day. Is it wrong? Definitely not and it may work in some instances, but the vast majority of the population would benefit greatly from eating LESS FREQUENTLY.

Doing daily intermittent fasting (IF) is already a great starting point for reaping the benefits fasting ketosis but there are many others uniquely characteristic to an extended fast that lasts for 24+ hours.

3 Day Fast Benefits

Is a 3 day fast safe? Is a 3 day fast healthy? Is a 3 day fast effective? The answer to all 3 of those questions is a big YES.

When tapped into a physiologically fasted state, the body goes through a series of adaptations:

Cellular Detoxification and Repair

While feeding, our body doesn’t have the desire nor the need to conduct thorough cleansing. The main mechanism for this is ‘autophagy.’

‘Autophagy’ is a metabolic pathway that causes the organism to ‘self-digest’ itself and removes waste material from the cells[i]. Autophagy is required to maintain lean body mass and it actually inhibits the breakdown of muscle in adults[ii]. It’s also needed for healthy brain cell mitochondria[iii]. In the process, inflammation throughout the body and overall oxidative stress get reduced[iv]. This fights against all illnesses and it’s the best thing about intermittent fasting.

Autophagy - One of Many 3 Day Fast Benefits
Autophagy – One of Many 3 Day Fast Benefits

Increased levels of glucose, insulin, and proteins all turn off autophagy. Even as little as 3 grams of the amino acid leucine can do so.

To release autophagy, your liver glycogen stores need to be depleted first. This takes up to 14-20 hours of not eating. However, this pathway will only reach its peak after fasting for 2+ days.

Boosts Growth Hormone and Retains Muscle

While fasting, the body shifts into a state of nutritional ketosis which is characterized by the production and utilization of an increasing amount of fatty acids and ketone bodies. This will torch fat burning as you’ll be drawing all of your fuel from the adipose tissue.

It also means that extended fasts aren’t as catabolic as you might think. The biggest fear people have in regards with fasting is that they will lose their muscle. This won’t happen because:

  • Ketosis is an anti-catabolic state that decreases the body’s need for glucose and makes you gain all of your energy from your own stored fat. Ketone bodies may rise up to 70-fold during prolonged fasting[v].
  • Fasting triggers Human Growth Hormone (HGH), which is the hormone responsible for the building, maintenance and preservation of lean tissue, including skeletal muscle, cells, and organs.

In fact, HGH increases within the first 16+ hours by an astonishing 1300-2000%[vi]. Only after extremely extended fasts, such as 10+ days will you see HGH flatting out[vii][viii].

Moral of the story: 3 day fast muscle loss – ZERO

Increased Metabolism

Contrary to popular belief, intermittent fasting doesn’t slow down the metabolism but actually increases it by 3.6% after the first 48 hours[ix]. Even further, 4 days in, resting energy expenditure increases up to 14%[x].

Instead of slowing down the metabolism, the body revs it up and puts it into a higher gear. This is probably caused by increased adrenaline so that we would have more energy to go out into the savannah and find some food.

Although you may experience an initial slump in your metabolism, it isn’t necessarily a bad thing nor a sign of fat gain. It’s just that, after you stop eating, your body becomes more conservative with its fuel.

Better Biomarkers

There are a host of health benefits accompanied by the leave of food. The key contributing factor to this is insulin. It’s the key hormone in regards to the storage and distribution of nutrients in the body.

Insulin gets released by the pancreas in response to food intake. When blood sugar levels start to rise, insulin gets unleashed and unlocks the cell receptors for the sugar to enter them. The purpose is to store energy and prevent having elevated blood glucose levels for too long.

Most modern cardiovascular diseases are caused by constantly high blood sugar and insulin levels. To overcome this issue, you would want to keep insulin as low as possible and fasting is the surest way of doing so.

Fasting will:

  • Fight diabetes and lowers blood sugar levels
  • Improves insulin sensitivity, meaning it makes your insulin work more effectively
  • Reverses insulin resistance, which is characterized by an irresponsive insulin, leaving your blood sugar elevated for a long time
  • Reduces cholesterol because while fasting, you’re not consuming any carbs and the liver will thus decrease its synthesis of triglycerides

Protection Against Cancer and Tumors

On a similar note, autophagy can also purge precancerous cells and cause the apoptosis (cellular death) of malignant tumors. This gets triggered by fasting for an extended period of time.

Dr. Dominic D’Agostino is the leading expert in the field of research on cancer, fasting, and nutritional ketosis. He advises everyone to have a therapeutic fast that lasts for 3-5 days 2-3 times per year. In so doing, you’re conducting deep cellular cleansing that will reduce your risk of cancer by a huge margin. Even if you’re healthy you would still want to take some preventative measures towards disease.

And Neurodegenerative Disease

Fasting also increases levels of a hormone called ‘brain-derived neurotrophic factor’ (BDNF)[xi], a deficiency of which has been implicated in depression and various other similar problems. New brain neurons get formulated, which is a process called ‘neurogenesis.’ What’s more, neuroplasticity – the brain’s ability to form neural connections – benefits from this as well due to BDNF[xii].

All that being said, fasting bolsters brain power and gives protection for neurodegenerative disease while mitigating cognitive decline.

Lengthened Life-Span

By the same token, fasting improves longevity. If autophagy and HGH are running rampant, then your body will experience less oxidative stress and inflammation, including ‘sarcopenia’ (muscle loss) which are one of the biggest contributing factors to aging.

Fasting induces oxidative stress because of producing a surge in free radicals – the molecules mostly associated with aging. This further stimulates a gene called SIRT3[xiii] to increase the production of ‘sirtuins,’ which are protective proteins of longevity. In mice, they extend lifespan. There are no studies in humans but the effects may be similar.

The rise in free radicals is actually beneficial because they trigger protective pathways. If the body is intermittently exposed to low levels of oxidative stress it can build a better response and cope with it better.

When you abstain an organism from calories for a certain period of time, their expected lifespan will increase by 30%, but they will eventually still starve to death. The key to actually gaining any benefits from this abstinence is to do it intermittently.

3 Day Fast Without Getting Hungry

After reading all of those benefits, how do you feel now? Is there still an impending feeling of resistance and fear? Or have you overcome the belief that fasting is bad and dangerous?

Whatever the case may be, you probably still want to know how to actually do it. To satiate your now reinvigorated thirst for knowledge and stray off hunger, I’ll give you an easy guide to fasting for 3 days.

The 3 Day Fast Formula

The First 24 Hours

  • The night before, have a low carb dinner so your glycogen stores would be depleted already. This will make your body enter into ketosis faster and induce autophagy that much quicker.
  • Wake up the following morning and drink a cup of water with a pinch of sea salt in it. This is done as to replenish your electrolytes and reduce cortisol.
  • Wait 1-2 hours and have a cup of green tea or herbal tea. Black tea has more caffeine in it so you would want to wait slightly longer for that.
  • Drinking sparkling water is also an amazing way to reduce hunger to zero
  • If you get your first real hunger sign, then drink some more water and wait for 15 minutes. If the feeling subsists, then have a cup of black coffee
  • You can drink decaf throughout the day as well but don’t drink it as a substitute for water or tea. The max should be 2-4 cups of coffee a day because it still dehydrates you.

A Word on Non-Caloric Sweeteners

Avoid diet-sodas or other artificial sweeteners. Despite their non-caloric content they still give rise to insulin, creating a placebo-like fed state.

  • Be productive. Do paperwork, read books, write something or anything else that keeps your mind busy.
  • Go for a walk. Low-intensity walking will increase fat burning in a fasted state and will thus actually make you feel like you’ve eaten.
  • Use apple cider vinegar to stray off hunger once it gets too difficult. get a glass of warm water and add 1-2 teaspoons of apple cider vinegar. Any more than that may have some unwanted consequences, so don’t go overboard.
  • Brushing your teeth is another option.
  • At the 20 hour mark. You can have a warm glass of lemon water or bone broth. Adding a teaspoon of ginger turmeric and cinnamon (in total) is also very cleansing. This is so called “dinner.”

To be honest, the first 24-hours are the only difficult part of an extended fast. This is due to your body still being geared towards burning its own glycogen supply. After this gets depleted, you enter into a deeper state of ketosis and gain access to your abundant fuel stores.

The Second Day

If you make it to bed at the end of the first day without feeling excruciating pain and hunger, you can consider the fast already a success. To be honest, it’s all downhill from there because your body will be buzzing with those endogenous ketones. Follow the same bullet points mentioned above and you’ll be glorious.

At the second day, your mind will also have been refreshed and reinvigorated. Although having not eaten anything for 30+ hours by now, your mind is still very sharp and clear. Of course, there are some limitations to this but, given the circumstances, you’ll feel quite amazing. The reason is that elevated ketone bodies lead to the accumulation of acetoacetic acid that produces a mild intoxication similar to that of ethanol[xiv].

What gets people most during fasting are social pressures and food signals from the environment. If your family is cooking a nice steak dinner with some steaming vegetables, then you’ll definitely get the urge to simply quit it and give in. What’s more, getting the runs over even just looking at food may cause an insulin response – that placebo effect is that strong.

So, unless you have the mental fortitude and sheer willpower to sit in front of a cake without having the desire to eat it, you would want to be in an environment with as little food induced stimulation as possible. Spend the time in solitude or have a short retreat.

Day Three

Going to bed at the end of the second day isn’t nearly as hard as during the first. Your body will have already adapted to creating energy from within and, what’s more, your mind has come out of the habit of eating.

This is a huge paradigm shift you’ll experience during extended fasts. You realize that you don’t have to eat every several hours. By now, you’re in day 3 and are feeling just fine. In fact, you’ll actually start enjoying it, but only some aspects of it.

Having naps throughout the day is also a great way to make time pass by faster and rest. When in a low energy state and already at a severe caloric deficit, you don’t want to waste your power on anything.

The 3 day fast should also be considered as a mental retreat and a period of downtime. Think of it as the ultimate cleansing of your body and mind. Don’t be stressed out or rushing and simply relax and recover.

Breaking a 3 Day Fast

It doesn’t really matter when you end your fast. You can finish your abstinence at around the 70-hour mark – you’ve achieved the main idea of it which is to not eat anything for 3 days.

Another option is to also continue fasting – go for 4 or 5 days, given you’ve already made it this far. Whatever feels suiting, but don’t feel the obligation to go any longer than that. There are no significant benefits to gain from abstaining for that long unless you’re either clinically overweight or have some other severe medical condition.

How to Break a Fast:

The worst thing you could do is start eating massive amounts of junk food, or any other food, really. This would cause stress to the intestines and your body needs time to readjust to food. Instead, what we need to do is slowly ease into it and be mindful of how to break a fast.

  • The best way to start off is with a glass of hot lemon water. The citric acid gets absorbed really quickly and promotes the production of good digestive enzymes in the gut – it gets the juices flowing. Drinking apple cider vinegar will wake up the intestines and prepares them for the feasting that’s to come.
  • Then, before having your actual first meal, eat something very small and low-glycemic, such as a half an avocado, a few nuts or vegetables.
  • Your first meal should be something small and low-glycemic. This will keep you in a semi-fasted state because of the non-existent rise in blood sugar. Carbohydrate refeeding after fasting causes an abrupt weight gain[xv]. A spike of insulin will help you shuttle nutrients into your cells but also has some negative side-effects.
  • After your first meal, wait an hour or two and continue with the second and third one. Wherever your dietary protocol may lie, you would still want to keep your blood sugar levels stable. Don’t start piling down tons of processed carbohydrates because that would only make your fasting counter-productive.

How Much Food Should You Eat?

An average person’s daily basal metabolic rate falls somewhere between 1800-2200 calories. During the fast, this may decrease slightly because the body won’t need that many thanks to ketones.

If you do the math, then not eating anything for 3 days creates a deficit of about 6000 calories. That’s quite a lot and it will definitely show. However, it doesn’t mean that you’ve actually lost that many calories. Like said, your body becomes more energy efficient and preservative, which reduces the amount of calories you actually burn while fasting.

Whatever the case may be, you wouldn’t still want to eat all of those 6000 calories back. This would yet again make fasting an easy excuse for binge eating.

In fact, you would even want to eat below your daily caloric demands on the day you break your fast. The reason is that your body still needs time to re-adjust to food. If you eat too much right away, your digestive process may react by causing diarrhea, fatigue, faint of heart and nausea.

  • On the day you break your fast, eat about 200-400 calories below your maintenance and call it that for the day.
  • The next day, however, you would want to fast for less duration and eat the same amount above your maintenance.
  • Continue to eat slightly above your maintenance for a third day and then re-adjust your intake according to your goals.

The 3 Day Fast on Keto

Is a 3 day fast worth it? Most definitely, I would even consider it effortless in comparison to the immense benefits you get.

Intermittent fasting should be a part of every healthy nutritional strategy. However, it works even better on some approaches than others.

Doing IF on a ketogenic diet is the best way to do it because the two are physiologically almost identical. Both of them shift you into a state of nutritional ketosis, in which you’re burning mostly ketones for fuel.

Fasting on keto is just so easy and you almost never experience hunger. Instead, you’ll have constant energy and vigor.

If you want to learn how to combine these two giants of strategies, then check out my KETO // IF program – it’s the 3 day fast diet plan and beyond.


P.S. Watch this video about my recent 3 day fast.

Stay Empowered



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