Exploring the Mental-Health Benefits of Fasting

Written and medically reviewed by Nicole Grant, RD

Fasting isn’t just about the body! If you’re interested in improving your mental health, consider fasting as a tool.

The Mental Benefits of Fasting

Many people embrace fasting for its physical benefits, but it’s easy to forget that the brain is part of the body, too! According to scientific literature, fasting has a considerable impact on the mind; it’s been tied not only to reducing stress, combating depression, and easing anxiety, but also to elevating mood, refining emotional regulation, and sharpening mental clarity.

Fasting for Stress Reduction

Finding the right balance between fasting and eating can help you manage mental stress. Although research is limited, a handful of studies have shown a positive correlation between fasting and mental-stress reduction. For example, people who followed a 16:8 fasting regimen (eating all of their meals within 8 hours and fasting for the other 16) for four weeks showed a significant decrease in the Perceived Stress Scale, leading to more positive thoughts and feelings towards daily stressors in their lives. People who follow the religious fasting practice of Ramadan also showed a much lower stress score at the end of the fasting period compared to the start. 

The mechanisms behind the stress reduction seen with fasting are not fully understood; however, some researchers attribute these positive changes to improved overall health and a better physiological stress response that translates to a reduction in mental stress. A less stressed body can lead to a less stressed brain!

Fasting for Depression and Anxiety Management

Intermittent fasting in alignment with your circadian rhythm may help with depressive symptoms and anxiety. For instance, participants showed much better scores for a depressed mood when following an early time-restricted feeding (TRF) protocol, where they ate between the hours of 7 a.m. and 3 p.m. (an 8-hour period coinciding with key waking and activity hours) compared to when they ate throughout a longer 12-hour period.

A few studies have also shown positive associations between fasting and anxiety. Many of these positive shifts may relate to the spiritual and social aspects of Ramandan fasting, but they may also be the result of improvements in BMI and overall health that were brought about by a consistent non-religious fasting protocol.

Fasting for Clarity and Enhanced Cognitive Function

Fasting initiates a metabolic switch where the body’s preferred fuel switches from glucose (the simplest form of carbs) to fat. This has plenty of implications for your body, but when it comes to your mind, it’s all about a byproduct of fat: ketones.

When your liver breaks down fat, it produces ketones, a unique fuel source that the brain in particular likes to use for energy. When the brain uses ketones as its primary energy source, it may operate more efficiently, leading to improved focus, clarity, and mental stamina.

Fasting for Better Emotional Regulation

Emotional regulation can be described as your ability to control your emotional responses in a variety of settings, thereby promoting emotional well-being and positive social interactions. The scientific literature on emotional regulation and fasting is still in its infancy; however, one study was able to show better responses to negative emotions over time. In this study, individuals with prior fasting experience had higher resilience scores and were able to recover from stressful events better than those new to fasting. Improved resilience can translate into better emotional regulation and ability to adapt to challenges, especially when tensions are running high. 

Fasting for Mood Enhancement

While you’re fasting, you can experience emotional states ranging from uncertainty and irritability to an increased sense of achievement and pride. However, many of the negative moods experienced while fasting are often related to inexperience. As your confidence and consistency grow, you may find that the short-term challenges and discomforts are worth the long term improvements in mood and overall well-being. 

Along with feelings of accomplishment, fasting is shown to encourage positive shifts in neurotransmitters, such as serotonin, that help regulate mood. While there is individual variation, intermittent fasting has been shown to increase serotonin transporter availability and serotonin levels, leading to higher levels of this “feel good” hormone in the body.

Fasting to Improve Sleep Quality

Research suggests that intermittent fasting improves sleep quality by reinforcing circadian rhythms. Your body primarily uses light and dark to determine sleep-wake cycles; however, food acts as a strong secondary signal, promoting wakefulness. Intermittent fasting — especially when you limit nighttime meals and snacks — can help you experience deeper sleep, including more REM sleep, and less daytime fatigue

Sleep quality has been shown to strongly predict the next day’s mood, with better sleep leading to better mood, lower rates of anxiety, and lower levels of self-reported minor depression. So, by using fasting to set yourself up for better, deeper sleep, you may be taking an important step towards improving your mental health.

Fasting for Neuroprotective Effects

Although more research is needed to fully understand the impact of fasting on neurodegenerative disease in humans, animal models show promise. Some studies have demonstrated improvements in Alzheimer’s, Parkinson’s disease, and stroke. The mechanisms behind these effects might be linked to several biological changes that occur during fasting. Specifically, increases in brain-derived neurotrophic factor (BDNF) and decreased inflammation — both of which can be elicited by fasting — can protect against damage to neurons and potentially slow cognitive aging.

Fasting to Improve Body Image and Self-Esteem

Intermittent fasting, along with balanced nutrition, exercise, and self-care, may contribute to improved body image and self-esteem. For many individuals, fasting provides a structured approach to eating that can lead to weight loss or positive changes in body composition. These physical changes, in turn, can contribute to a more positive body image and elevated self-esteem. Beyond the external transformations, the act of fasting itself can instill a sense of accomplishment and mastery, reinforcing the belief in one’s ability to set, stick to, and achieve personal goals. 

Understanding Fasting

What Is Fasting?

Fasting is abstaining from caloric foods or beverages for a period of time generally ranging from 12 hours to multiple days. It is a practice that has been observed for centuries, often for cultural, religious, or health reasons. During fasting, the body’s primary energy source shifts from consumed food to stored energy reserves, such as glycogen and fat.

Fasting can take various forms, including intermittent fasting, where periods of fasting alternate with periods of eating. The most common form of fasting is time-restricted feeding (TRF), in which individuals consume all of their daily calories within a specific window of time, typically 4–12 hours. Outside of this window, they keep their intake calorie-free, focusing primarily on water, herbal teas, or other non-caloric beverages.

The practice of fasting can have potential benefits, including weight loss, improved insulin sensitivity, enhanced metabolic health, and — as some research suggests — positive effects on aspects of mental and emotional well-being. 

Types of Fasting

People may choose to follow several types of fasting regimens for various health, religious, or personal reasons. Each type of fasting involves specific patterns of when to eat.

Time-Restricted Feeding (TRF)

This form of intermittent fasting involves eating only during specific hours of the day. The most common example is the 16:8 method. Other combinations range from 12:12 to 20:4.

5:2 Fasting

This consists of ordinary caloric intake for five days a week and two non-consecutive fasting days that consist of significantly reduced calorie intake (typically around 500 calories or less).

Alternate-Day Fasting

This method alternates between fasting days and habitual eating days.

Prolonged or Extended Fasting

These are multiple-day fasts with little to no caloric intake during those days.

It’s important to note that while fasting has shown potential health benefits for some individuals, it might not be suitable for everyone, especially for people with certain medical conditions, pregnant or breastfeeding women, and those with a history of eating disorders. Consult your doctor before starting any fasting regimen to determine the suitability of fasting to your individual health needs and goals.

How Fasting Affects the Body and Brain

Fasting instigates a series of metabolic and cellular changes that affect both the body and brain. In the body, fasting triggers a shift from glucose metabolism to the mobilization of fat stores, resulting in the production of ketone bodies. These ketones, specifically beta-hydroxybutyrate, serve as an alternative energy source, and their presence in the bloodstream has been associated with enhanced brain function and neuroprotection. 

Within the brain, fasting stimulates the production of BDNF, a protein that supports neuronal health and growth. Additionally, fasting can induce autophagy — a cellular “clean-up” process that helps remove damaged components — in brain cells, potentially offering protection against neurodegenerative diseases. Furthermore, fasting may reduce oxidative stress and inflammation, two factors implicated in aging and various chronic conditions.

The Connection Between Fasting and Mental Health

Intermittent fasting protocols have been shown to influence a variety of processes in the body that impact neurotransmitters, hormones and autophagy — ultimately benefiting mental health. 

Neurotransmitters and Hormones

Neurotransmitters and hormones are messenger molecules that enable connection between organs. Interestingly, fasting can have an influence on these types of molecules.

Norepinephrine, a compound that can act as both a neurotransmitter and hormone, is often associated with alertness and attention. Fasting has been shown to increase levels of norepinephrine, which can explain the heightened focus some fasters experience. 

Serotonin, frequently termed the “feel-good” neurotransmitter, is instrumental in mood regulation, appetite control, and sleep patterns. An increase in its levels, as sometimes seen with fasting, can potentially lead to improved mood and reduced depressive symptoms.

Brain-Derived Neurotrophic Factor

Preliminary evidence shows that fasting can increase the production of BDNF. Elevated BDNF levels have been linked to improved cognitive functions, increased resilience to stress, and protection against neurodegenerative diseases. Thus, fasting offers a potential strategy for bolstering cognitive health and guarding against aging-related declines.

Cognitive Benefits

As mentioned, intermittent fasting can have some short-term benefits to cognition and mental clarity related to the switch in fuel from glucose to ketones. Furthermore, an improved gut microbiome, which enhances the gut-brain axis, can lead to better cognitive function. Some studies have also shown a link between intermittent fasting and long-term brain health. In fact, one study found that regular intermittent fasting was able to reverse mild cognitive impairment in about 25% of the participants with this condition.

Emotional Well-Being

Early days of fasting can be somewhat of a mental and emotional roller coaster, but those who are able to successfully find a routine that works for them can experience improved emotional well-being. Studies have shown that even in the short term, participants are able to experience a sense of achievement, reward, pride, and control while fasting. When you feel like you are taking care of yourself physically, your emotional health can improve as well.

Autophagy and Cellular Repair

Autophagy is a vital process in the body that is responsible for cleaning up damaged cells. Research has shown that fasting acts as a potent stimulator of autophagy, particularly in the brain. Enhanced autophagy in brain cells can promote the removal of excess proteins and damaged mitochondria, the powerhouse of the cell. By clearing out these harmful components, autophagy can help optimize function and may even lead to a decrease in neurodegenerative diseases, such as Alzheimer’s. 

Precautions and Considerations

While fasting can offer many potential health and mental health benefits, it’s important to approach it responsibly.

Fasting is not suitable for everyone at all times. Fasting is not recommended if you:

  • Have a history of eating disorders or disordered eating, including anorexia nervosa or bulimia nervosa
  • Have other medical conditions, including type-1 diabetes
  • Are pregnant, breastfeeding, or trying to become pregnant
  • Are under the age of 18
  • Have a BMI of less than 18 or are already undernourished

If you have questions or concerns about whether or not fasting is right for you, seek the advice of a qualified health professional, such as your doctor or registered dietitian. Rapid changes in diet and eating patterns can also potentially trigger anxiety in some individuals, so be mindful as you get started on your fasting journey and seek professional assistance if the need arises.

Fasting for Mental Health Safely and Effectively

Download the Zero App

Healthy habits start with choosing the right tool, and Zero is the ideal partner for your fasting journey. The app helps you track your progress, stay motivated, challenge yourself, and learn more from scientific and medical experts who can guide you through decision-making as you pursue improvements in your physical and mental health.

Start Gradually

It may be old advice, but it is true: Starting small is the best way to cultivate a new habit, including fasting! When it comes to fasting, this is particularly true, since it takes time for your body to learn how to flip the metabolic switch and burn stored fat (instead of glucose from food) more efficiently. Over time, your body will become less reliant on glucose, making fasting easier. 

Start gradually with a fast of 12–15 hours several times a week to give your body and brain a chance to adjust to the intermittent fasting lifestyle. Remember, sleep counts towards your fasting goal, so by moving breakfast later or dinner earlier (or a little of both!), you can easily hit your fasting target. Once this feels easy, you can increase your fast length until you find a schedule that suits your mental- and metabolic-health goals. 

Prioritize Nutrition

During eating periods, choose a wide variety of minimally processed, nutrient-dense foods to meet your nutritional needs. The Mediterranean diet, an eating style rich in minimally processed fish, vegetables, fruit, and olive oil, as well as the Japanese dietary pattern, rich in vegetables, fruits, seaweed, green tea, and soybeans, have both been linked to improved mental health, including lower rates of depression. In contrast, the modern Western diet, hallmarked by high fat, high sugar, ultra-processed foods and lower consumption of fruits and vegetables, has been linked to higher rates of depression, anxiety, and neurodegenerative disease. 

If your overall diet is already in pretty good shape, you might consider concentrating on a number of specific antioxidant nutrients that have shown a protective effect against poor mental health. Polyphenols (found in high concentrations in green tea), omega-3 fatty acids from salmon and walnuts, and flavonoids in blueberries and other fruits and vegetables have been shown to reduce depression and improve cognition and overall mental well-being. 

Keep Up the Consistency

Consistency is key to “feeling good” while fasting. Experience with previous fasts has been shown to create a “buffer” against negative emotions while fasting. A reduction in appetite, less frequent negative moods, less stress, and more vitality can be seen with more seasoned fasters compared to those who are new to fasting. So, tap into Streaks, Challenges, and all the motivational features of Zero to keep your fasting practice going day after day.

Stay Hydrated

Hydration is essential for optimizing both physical and mental health. Studies show that even mild dehydration of less than 2% of body weight can have a negative impact on cognitive performance, mood, and feelings of physical well-being. Therefore, drink plenty of water during your fasting and eating windows, and don’t forget electrolytes!


Fasting offers one tool, among many, to improve your mental health. It offers cognitive benefits, promotes emotional well-being, and initiates cellular repair mechanisms. However, the connection between fasting and mental health is a complex interplay of physiological and psychological factors, so fasting should be adopted mindfully, with consideration for individual health history and goals. Keep in mind that fasting may not be the only tool you need, so if professional mental-health help is necessary, please seek it out.

Finally, when incorporating fasting into your routine, make adjustments gradually and focus on proper nutrition and hydration during your eating window to help make the experience as smooth and comfortable as possible. Then, stick to it! The more consistent you are, the more likely you are to reap mental health benefits from your fasting practice.

Nicole Grant, RD
Posted in Health & Science

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