Intermittent fasting is one of the most popular trends in the health & wellness industry. From weight loss, anti-aging, and cognitive function to lower inflammation, it can be effective. But what is intermittent fasting for real?

Take it from a long-term fan who has been fasting for the past 5 years (me, although I’m only 23) and blame it on my desire to increase growth hormone secretion. This is the holy grail on how intermittent fasting works, its effects, and benefits on the body. Enjoy!

What is Intermittent Fasting

Intermittent Fasting is pretty self-explanatory. Intermittent means something is not continuous, but intermittent, occurring at intervals. Fasting is abstinence from eating food. Intermittent fasting means you are eating and not eating at specific time intervals during your day.

It’s not that much about what you eat, but when you eat it. It is about not eating food for certain intervals of time. This is thought to promote many health benefits if done properly. We are talking weight loss, anti-aging, cellular cleansing or detox, increase in growth hormone, improvement in insulin sensitivity, etc. (you get the idea)

But why would I starve myself you might ask? Well, there is a massive difference between starvation and intermittent fasting, check it out.

Intermittent fasting vs. Starvation

Our primal ancestors didn’t have the fancy lifestyle we have. Food was something they haunted for, not something they got whenever they wanted. Their supermarket was nature, and they had to find ways to survive when they couldn’t eat. Some of them starved, and some of them fasted, but what’s the difference?

Starvation is a continuous and severe caloric restriction of calorie intake deficiency, which is below the optimal levels to support our vital functions. This means not eating sufficient food for extended periods, resulting in stunted growth, severe weight loss, brain shrinkage, muscle loss, and bone loss. During starvation, the body eats or breaks down functional and vital tissues like bones, muscles, and organs to produce energy.

During intermittent fasting, we only expose ourselves to short-term food abstinence, which has numerous health benefits. It can promote a sort of internal cellular cleansing or autophagy, during which the body breaks down dysfunctional cells and flushes out toxins and waste products.

Simply put, not eating for 16 hours won’t eat your vital organs, but may burn some of the excess fat around your belly. So far, sounds good aye?

Types of Intermittent Fasting

There are different fasting protocols that can have different effects on health. While some are more suitable for autophagy, inflammation reduction, and longevity promotion, others are better to boost growth hormone, improve athletic performance and shred extra fat. We’ll discuss these in-depth in another article, but let’s see the most common types.

Which Intermittent Fasting Protocol is the best?

There isn’t one significant method of fasting that outperforms all the others. Longer fasting protocols like 5-days have been shown to skyrocket HGH secretion up to 300%, (1) while 16/8 shorter fasting in conjunction with resistance training showed a decrease in fat-free mass, muscle gains, and maximal strength. (2) Periodic fasting of 2-7 days once per month may have a positive effect in slowing down cellular aging, lowering inflammation, and preventing diseases. (3)

7 Effects of Intermittent Fasting

As we’ve seen, fasting was a part of the lifestyle of our primal ancestors. There are many benefits from intermittent fasting which we’ll talk about. Keep in mind some of those are done in animal models, some in humans.

Either way, there are many effects on different biomarkers like cholesterol, growth hormone, inflammation markers, etc. which give us a good picture of why fasting can stimulate autophagy, and how it can help us be healthier, stronger, and live longer.

1. Increase in Human Growth Hormone

(Not Necessarily Muscle Anabolism)

The fountain of youth, the elixir of life, and the master of muscle gains, HGH. HGH is known as the main muscle growth and anti-aging or weight-loss hormone, and while some of that is true, there are so many other factors affecting these effects.

HGH is an important hormone involved mainly in the growth, development, metabolism, regeneration, and building of tissues. It has a profound effect on organs, bones, muscles, and the brain. It up-regulates IGF-1 production which has a profound effect on metabolism. It increases protein synthesis, and amino-acid uptake and reduces muscle degradation. (4)

Unfortunately, as impressive as it sounds, HGH from fasting might not be the most convenient way to grow muscles. Why? Long-term 26-day fasting has been shown to skyrocket HGH by 1250%. Yes, sure. But HGH was increased to stimulate protein synthesis and spare the muscle, it is an automatic response for survival. Not eating for so long will eventually result in muscle loss, hence why our body produces such excess amounts of HGH. (5)

However, the good news is fasting for 16 hours can produce a smaller, but still significant rise in HGH levels. The body won’t eat its own muscle tissue for energy during such a short period of fasting (16h). This means a high protein diet, with 16 hours of fasting may result in greater muscle anabolism.

2. Accelerate Weight Loss and Fat Loss

The main reason behind the weight loss and fat loss effects of intermittent diet lies in glucose metabolism, insulin hormone regulation, and potential caloric restriction.

First of all, let’s check caloric restriction. Many people don’t even try to eat fewer foods, but due to the restricted eating window, they aim for less food because they can skip one meal (breakfast usually). After skipping that one hunger trigger you’ve already reduced the calories of your first meal.

Alternate-day fasting, the 5:2 diet, or even time-restricted eating were all shown to be effective for weight loss. Participants in this study reduced their weight by 1-8%, partially due to the reduced caloric intake of 10-30% (with improved appetite regulation). (7)

It seems as if intermittent fasting isn’t superior to continuous energy restriction, for weight loss at least. (8) However, it may be a more practical option to adapt, which comes with other benefits like HGH increase, mental alertness, and anti-aging.

3. Improve Insulin Sensitivity and Blood Sugar Control

Overeating, or consuming higher caloric intake than the energy we expend results in gaining weight. Mostly, people who overeat increase their weight which also causes metabolism disruption and hormone imbalances that favor diabetes.

A 2020 review that took a look at 27 trials showed that intermittent fasting resulted in a 0.8 to 13% reduction in body weight and 4.3% reduction in body mass index. All this without significant hunger problems, energy crashes, and sugar fluctuations. Fasting showed potential for improving glycemic control but might be risky for people with hypoglycemia. (9)

Even without significant weight loss, in prediabetic men, intermittent fasting was superior to a regular diet for improving insulin sensitivity, glycemic control, and other cardiometabolic markers like blood pressure and oxidative stress. The protocol here involved early time-restricted eating, meaning they ate early in the day but had their dinner till 3 pm. (10)

By skipping breakfast, or reducing the intake of sugar throughout the day, we can reduce chronic insulin elevation. This means the body won’t secrete so much insulin, as there’s no demand for it, since we don’t eat so much sugar. Instead, we’ll metabolize fats for fuel while having lower insulin levels, thus resulting in burning fat.

Of course, fasting should always be practiced cautiously in people with blood sugar regulation problems, children, pregnant women, and other specific populations. So always speak with your doctor first.

4. Promote Autophagy or Cellular Cleansing

Autophagy is a self-preservation mechanism that is highly linked to longevity and anti-aging. The word itself means self-eating. It is the way your body eats itself, to clean itself.

During our lifetime we change our bodies almost from scratch (maybe with the exception of neurons) many many times. While it seems creepy that you aren’t the exact same person as 2 years ago, don’t worry, your DNA makes sure you look pretty much identical.

Autophagy is a natural process of removing dysfunctional cells, flushing out toxins, and removing damaged structures. Stressing our bodies through food abstinence can actually be beneficial, as it is one way to stress our body to stimulate adaptation, to kick start your regeneration and anabolism capabilities.

• Research shows that fasting and calorie restriction are some of the most potent simulators of autophagy. (11)
• There is also data that sporadic fasting can induce neural autophagy, which may potentially improve brain function, reduce inflammation and prevent neurodegeneration. (12)

Autophagy is a way of cleaning your body from the inside out. It’s a sort of cellular cleansing which removes dysfunctional proteins. During a calorie restriction, this is one of the reasons we lose fat. Because the liver converts extra glycogen to glucose first, once we deplete it, the liver breaks down fats for energy.

5. Lower Inflammation and Oxidative Stress

Oxidative stress, free radicals, and inflammation go hand in hand. Chronic inflammation and excessive oxidative stress are contributing to the development of the most common diseases. (13)

But if you fear inflammation, you can stop. Inflammation is the natural process after any stressors. And we need stressors to adapt. To grow muscle or lose weight, we exercise, and this causes inflammation. It is an automatic adaptation response. The problem is chronically elevated inflammation that degrades us.

• Inflammatory markers, cytokines, and monocytes are the way we measure inflammation. Research shows that short-term fasting can have profound metabolic effects and reduce inflammation, falling along with the number of monocytes. (14)
• It is no secret that caloric deficit or intermittent fasting reduces inflammation and has the potential to attenuate pro-inflammatory cytokines. (15)

Think of oxidative stress as aging. High levels of it damage our DNA. Then the body becomes inflamed to respond to this. However, our body has its limits to how much inflammation it can fight.

Restricting caloric intake or fasting can promote longevity, mainly by reducing oxidative stress. IF dieting is a better, more practical long-term alternative that acts in a similar way. (16)

6. May Aid in the Prevention of Various Diseases

Intermittent fasting has so many different effects and benefits that can be synergistically related. To show you what I mean, look at the next pattern.

We’ve shown it increases HGH, improves insulin sensitivity, lowers inflammation, blah, blah.. When you combine these benefits the synergistic effects can be significant for our health. Because diabetes or obesity is tightly related to inflammation, which is related to neurodegeneration, cancer development etc.

It all goes back to autophagy, the self-preservation method. It is about removing dysfunctional cells, lowering inflammation, and reducing oxidative stress. Here are a couple of studies of intermittent fasting on disease prevention, showing some potential effects:

7. May Increase Alertness and Protect The Brain

If you’ve ever loaded up on carbohydrates (which you have) you already know the sleep-inducing effects. More blood travels to your digestive system, to support digestion, putting you in a rest-and-digest state.

Intermittent fasting acts similarly to the keto diet in this regard. It is known that by abstinence from carbohydrates we can improve mental clarity, increase alertness and elevate cognitive function. Because we are less sleepy because fueling the brain with ketones gives more sustainable energy. (21) (22)

There is an interesting neurotransmitter called Orexin, which is known to promote alertness and wakefulness. Research shows that Orexin-A levels were higher for the individuals that were fasting. (23)

Neuroprotection may also come as a result of reducing insulin resistance and preventing obesity, as these two cause high inflammation in the body. Other mechanisms like reducing neuroinflammation and increasing BDNF or brain-derived-neurotropic-factor (important in growth, differentiation, and maintenance of neurons) can also aid in the prevention of neurodegeneration and improving cognitive function. (24)

Intermittent fasting has been shown effective in ameliorating neurodegeneration in both animals and humans. There are potential benefits for ameliorating neurodegenerative diseases mainly evoked by metabolic and cellular mechanisms which may produce functional changes in the brain. (25)

Frequently Asked Questions