Why intermittent fasting actually works (it’s not what you think)

Intermittent fasting has been all the buzz these last couple years.

Whether it be for energy, cognition, fat loss, or even longevity, it’s almost always recommended. As if it’s some kind of “wonder strategy”.

There are many purported health benefits or why people deem it to be important, but I want to give you one very overlooked reason why it works.

It eliminates gut irritation during the period of fasting.

If you’re prone to digestive issues or have food sensitivities, then you tend to feel slightly worse when you’ve eaten. So when you fast, you feel better. So it’s not the fast or the fat-burning, or autophagy or whatever that makes you feel better. It’s the reduction in gut irritation and subsequent inflammation.

Eating foods that irritate your gut or that can potentially cause leaky gut, such as gluten, lectins, endotoxins, starches, etc., cause inflammation.

Fasting and endotoxins

Let’s take for example endotoxins or bacterial by-products. Gram-negative bacteria have endotoxins in their cell wall, so when they die, the endotoxin is released. These endotoxins can then bind to the toll-like receptor family in the gut lining and stimulate the immune system, which creates inflammation.

So if you have too much gram negative bacteria that release endotoxin, you’ll be in a chronically inflammed state. However, when you fast, endotoxin production reduces and inflammation goes down as well.

And when inflammation goes down, you start to feel better.

You start to feel:

  • More energy
  • Better cognition (less brain fog)
  • Better mood
  • Clearer vision
  • Fewer skin issues
  • Less joint pain
  • Higher libido
  • etc.

Intermittent fasting lowers endotoxin-induced inflammation

As already mentioned, intermittent fasting or fasting, in general, can lower endotoxins. This study found that intermittent fasting in rats reduced levels of mRNAs encoding the endotoxin (LPS) receptor TLR4 and inducible nitric oxide synthase (iNOS) in the hippocampus.

IF fasting also reduced the subsequent inflammation, evident by lower inflammatory markers, such as IL-1α, IL-1β and TNF-α levels (R).

The effect of this all results in improved brain function and less mood disorders, such as anxiety, depression, etc.

Intermittent fasting modulates gut bacteria

There is evidence that IF can “positively” modulate the gut bacteria, which also leads to lower overall inflammation (R). 

This remodeling is most likely due to lower inflammation, as inflammation causes gut dysbiosis, shifting gut bacteria to a more inflammatory type.

However, the study also found that administrating 3-indolepropionic acid (IPA), serotonin, short chain fatty acids (SCFAs) or tauroursodeoxycholic acid (TUDCA) showed a similar effect to IF in terms of improving cognitive function (R, R). As a side note, IF increases TUDCA levels in the gut.

IPA is a microbial deamination metabolite of tryptophan. It’s a potent neuroprotective antioxidant. Higher plasma concentration of IPA was associated with lower type 2 diabetes risk and it’s also been well reported for its role in preventing neuronal damage (R).

TUDCA is a potential neuroprotective agent and it’s been reported that TUDCA treatment prevented cognitive deficits via improving mitochondrial function and reducing neuronal death (R). If you want to learn more than about the awesome benefits of TUDCA, read this article of mine.

Excess fasting can be detrimental

Excess fasting on the other hand has the potential to be problematic. Alternative day fasting might exacerbate the immune reaction and subsequent inflammation to viral infections through TLR3 (R).

Intermittent fasting in mice led to the enrichment in Lactobacillus and the reduction of Akkermansia (R). This can be problematic as too much Lactobacillus can create too much lactate and overburden the liver, whereas a reduction in Akkermansia could lead to leaky gut, insulin resistance, etc. Read more about the benefits of Akkermansia muciniphila here.

Furthermore, in this animal study, alternate-day fasting decreased weight gain and food intake. Surprisingly, the IF regiment also elevated plasma insulin concentrations, both at baseline and after glucose administration during OGTT. After 12 weeks of dietary intervention, pancreatic islets displayed increased ROS production and apoptosis, meaning pancreatic damage. Despite their lower body weight, the animals that did IF had increased fat reserves and decreased muscle mass.

As a summary of the findings of that study, alternative day fasting in animals promoted β -cell dysfunction, insulin resistance, fat gain and muscle loss (R).

Last but not least, many studies have reported adverse outcomes as a consequence of
IF and they include (R):

  • Hypoglycemia, ketoacidosis, dehydration, hypotension, and thrombosis in diabetic individuals.
  • A significant increase in blood pressure and total cholesterol in middle-aged men.
  • Increased plasma concentrations of cortisol at night, which suggests altered circadian rhythms.
  • Higher peaks and more abrupt declines in insulin and glucose concentrations, indicating a biological environment prepared for long-term insulin resistance and diabetes.

A few alternatives to fasting

Not everyone wants to fast as they are too hungry in the morning, get low blood sugar, etc., but still want to reap the benefits of that clearheaded energetic feeling from intermittent fasting.

Here are a few alternatives to fasting that you can try out:

  • Eliminate all problematic foods from your diet that might be causing gut dysbiosis, leaky gut and inflammation in the first place.
  • Use activated charcoal. Activated charcoal helps to clear bacterial products and endotoxins from the gut. Many people feel better energy and more clearheaded when they use 1/2 tsp activated charcoal every morning or at least 2-3 times per week.
  • Do a fruit fast, which is basically when you eat whole fruits and/or drink fruit juice during the fasting period.
  • Drink bone broth in the morning. It’s very easy to digest and will provide a good amount of salt for those that crave something salty in the morning. Add well-cooked meat to the bone broth to up protein intake if you can tolerate it.
  • Use TUDCA. As one of the studies above pointed out, they could replicate the cognitive benefits of IF with TUDCA.
  • Lower overall inflammation


It appears that it comes back to the gut yet again. If you have had nagging gut issues that you want to clear up, then check out my Alpha Energy Nutrition Course.

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3 Replies to “Why intermittent fasting actually works (it’s not what you think)”

  1. Hans what are your thoughts on a 24 hour fast once a week? Never liked the way I felt on daily IF and moved to one 24 hour fast a week for the iapoptosis benefits. Thanks!

    1. Hey Scott,
      Yes I also like the idea of 1 full of fasting instead of shorter fasts. I think it’s more effective and less stressful that way.

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