The Psychological Benefits of Intermittent Fasting

18 October, 2020
Have you ever practiced intermittent fasting? It's all the rage these days. If you've never tried it, reading about the benefits might inspire you to start.

We live in the age of diets. There are diets to detox your body, ketogenic diets to lose weight, diets for gut health, eco-friendly diets, paleo diets… The list goes on. Lately, one very popular diet is called intermittent fasting, which has as many critics as it does supporters.

What’s involved in the practice of intermittent fasting? What are its physiological, psychological, and cognitive benefits? Today, we’ll share with you some of the reasons it’s so popular right now.

What’s intermittent fasting and how is it done?

Intermittent fasting is a way of eating that involves more-or-less structured periods of fasting and consumption. It means completely or partially abstaining from eating for a specific amount of time during the day before eating regularly again. When you do eat, your meals should be balanced to make sure you’re getting the nutrients your body needs.

While you’re fasting, you’re not supposed to eat anything. However, there are certain foods you can consume without “breaking” the fast. These include tea, infusions, black coffee, kombucha, bone broth, and vegetable broth.

There are different ways to practice intermittent fasting. If you think about it, everyone practices intermittent fasting to some extent, which is why we call the first meal of the day “breakfast”. You’re breaking the fast you kept while you were sleeping. However, some periods of intermittent fasting are longer. If you’re going to try to go longer without eating, you have to do it gradually. Let your body get used to longer windows of time without food. Below, we’ll talk about the most common types of fasting.

The 12-hour fast (12/12)

This type of fasting is the best option for beginners because it’s easy to do and doesn’t require a lot of sacrifices. All you have to do is make sure that you completely abstain from food for twelve hours after dinner. Thus, if you eat dinner at 7 p.m., don’t have breakfast the next day until 7 a.m. If this mirrors your regular schedule already, then great! You’re practicing intermittent fasting without even realizing it.

If that schedule doesn’t work for you, you can also fast between breakfast and dinner. 

The 16-hour fast (16/8)

Some people call this fast the “Lean Gains” fast. Here, the period of fasting increases to 16 hours, leaving you just eight hours during the day to eat. Studies about intermittent fasting typically focus on this type of schedule. It’s also the most popular and the easiest of the diets with longer periods of fasting.

Most people fast between dinner and lunch the next day, skipping breakfast. A lot of athletes practice this kind of intermittent fasting, as well as heavy weightlifters and Crossfitters, as a way to increase muscle mass.

The 20-hour fast (20/4)

This is also known as the warrior diet. Its long fasting period makes it a challenging practice. The best way to do it is to have a well-balanced large meal at the end of the day to make sure you’re properly nourishing your body.

The idea behind the 20-hour fast is that the paleolithic man was a natural “nocturnal eater”. That’s because they spent the day hunting and did all their eating when they finished.

This is strict but not as challenging as the 24- and 48-hour fasts. Those more extreme methods should only ever be done occasionally and under the supervision of a physician. If you’re interested in those more intense fasts, it’s important to gradually get your body used to fasting.

Physiological benefits

Intermittent fasting seems to be the more “natural” than the way most of us eat every day. We eat in a mechanical way, following an arbitrary schedule and eating at “correct” times whether we’re hungry or not.

Periodic fasting can be very beneficial for your body. Here are some of those benefits:

  • Increased autophagy and bowel movements, which help “clean out” the gut.
  • Fasting reduces inflammation and oxidative stress.
  • Improved metabolic flexibility, which increases your metabolism.
  • Greater sensitivity to insulin.
  • Increased growth hormone production.
  • Better weight control.

Psychological benefits of intermittent fasting

These physiological benefits of intermittent fasting also lead to cognitive and psychological benefits. They are:

  • Increased concentration. From an evolutionary standpoint, it’s important to remember that, after you eat, your cognitive function slows. That’s because your parasympathetic nervous system takes over after you eat. That de-activates your sympathetic nervous system, which is responsible for many of your cognitive functions. Studies also suggest that your level of neurotransmitters associated with concentration, such as noradrenaline and orexin, are higher during periods of fasting.
  • It can enhance neuroplasticity, which is the brain’s ability to create new connections. Being in the metabolic state of ketosis and alternating between different ways of getting energy encourages brain plasticity.
  • It can protect against depression. There’s a substance in the brain called BDNF (brain-derived neurotrophic factor) that’s nearly absent in people who are depressed. Consequently, encouraging the production of BDNF protects you from depression and intermittent fasting can foster BDNF production.
  • It can protect you against inflammatory processes. Inflammation can interfere with normal nervous system functioning. During the inflammatory process, your body sends its resources to fight inflammation and takes energy away from cognitive function. Therefore, if you reduce the inflammation in your body with periods of fasting, your body can use its resources more effectively.
  • Intermittent fasting can improve your relationship with food. Eating can become a kind of obsession or a pastime. Have you ever find yourself standing in front of the fridge because you’re bored? Re-calibrating your relationship with food can help you recognize feelings of hunger and fullness. That’ll make it easier to avoid emotional eating.
  • It can reduce mental fatigue. Eating a lot of sugar or highly processed foods can cause insulin spikes, which lead to mental fatigue. Eating whole, unprocessed foods after fasting can help reduce these spikes.
Food on a plate representing intermittent fasting.

Intermittent fasting isn’t for everyone

While intermittent fasting has psychological and physiological benefits, it isn’t for everyone. Women who are pregnant or breastfeeding, people with type 1 diabetes, people with very low BMIs and/or eating disorders, children, and people with liver failure shouldn’t fast.

Intermittent fasting does have some drawbacks as well. It can trigger an obsession with food, make you anxious, or lead to binging during non-fasting periods. This could cause eating disorders such as binging disorder or bulimia nervosa.

Therefore, if you fall into any of the above categories, intermittent fasting isn’t for you. If you don’t, why not give it a try? It could give your health and well-being a big boost. Lastly, always talk to a medical professional before trying any new diet.

Li, L.; Wang, Z. & Zuo, Z. (2013). Chronic Intermittent Fasting Improves Cognitive Functions and Brain Structures in Mice. PLoS One, 8(6): e66069.

Mattson, M.P.; Moehl, K.; Ghena, N.; Schmaedick, M., Cheng, A. (2018). Intermittent metabolic switching, neuroplasticity and brain health. Nature reviews Neuroscience, 19(2): pp. 63 – 80.

Shojaie, M; Ghanbari, F.; Shojaiec, N. (2017). Intermittent fasting could ameliorate cognitive function against distress by regulation of inflammatory response pathway. Journal of Advanced Research, 8(6), pp. 697 – 701.