Does Fasting Have Mental Health Benefits?

Fasting seems to be a bit of a health craze these days, with proponents of it guaranteeing all kinds of results, from quick weight loss to boosted mental clarity. Here’s the thing: there’s actually some solid evidence that intermittent fasting as a dietary intervention has health benefits, including reductions in body weight, cholesterol, blood sugar, and blood pressure.1 The question is: can fasting have positive effects on our mental health?

While there is some preliminary research linking fasting to improved moods, vitality, decreased irritability, lowered stress and even a reduction in depression and anxiety, there are other studies that show that short-term fasting can increase depression, anxiety, anger and irritability. The available research is relatively new and based on small sample sizes.2

Let’s take a closer look at the mental health effects of fasting, including benefits, risks, and how to do it, along with some expert guidance along the way.

What Is Fasting, Exactly?

First, it’s helpful to understand what fasting is. Fasting as a mindful dietary choice isn’t all about arbitrarily skipping meals or going without food for days on end. People who fast for health and well being do so deliberately, following one of several methods.

The most common type of fasting is intermittent fasting, which may take several different forms. Many people who practice intermittent fasting go for 12-18 hours each day without eating, and also have a 6-12 hour period where they do eat.

This eating period generally takes place in the daytime hours, and most of the fasting period takes place at night. For many people, intermittent fasting simply means skipping breakfast or having mealtime end early in the evening, along with no nighttime snacking.3

Another type of intermittent fasting involves fasting for longer periods, but only doing so several days a week. For example, in alternate-day fasting, people restrict their calories by about 25%, but only do this every other day, and eat normally on the other days. Other similar plans include the 5:2 plan, which is where you fast (or reduce calories significantly) two days a week but eat normally on the other days.2

Effects of Fasting on Mental Health and Emotional Well-Being

So, does fasting have any positive effects on mental health and emotional well being?

From what we know right now, it’s a bit of a mixed bag, says Clifford Feldman, MD, psychiatrist and medical director at Solace Treatment Center. “Fasting can have a variety of effects on mental health, depending on the length of the fast, the frequency of fasting, and an individual’s overall health and lifestyle,” Dr. Feldman.

As Dr. Feldman notes, there’s some research pointing to the fact that short term fasting can sometimes actually increase symptoms of depression, anxiety, anger, irritability, and stress. “However, some studies indicate that, with proper management, fasting can improve mood and emotional well-being in certain situations,” Dr. Feldman says.2

Ila Dayananda, MD, MPH, OB-GYN and chief medical officer of Oula Health, agrees that fasting can have a positive effect on mental health, but it varies from one person to another.

Dr. Dayananda says that the benefits may vary based on what type of fasting you do. Shorter fasting periods “may improve mental clarity and focus for some individuals,” she says. At the same time, “prolonged or extreme fasting may contribute to mood disturbances and cognitive impairments,” Dr. Dayananda  notes.

Fasting and Brain Function

There’s some pretty fascinating info out there about how putting your body in a fasting state can affect the brain—and in turn, how this might affect mental health.

Fasting affects brain function in a few different ways, Dr. Feldman says. It has been linked to neurogenesis or the development of new neurons, which can improve brain health and cognitive function.4

Additionally, fasting increases something known as brain-derived neurotrophic factor (BDNF). BDNF is important for learning, memory, and mood regulation, Dr. Feldman says.

Fasting impacts brain function via various mechanisms, says Dr. Dayananda, including “changes in neurotransmitter levels, alterations in energy metabolism, and activation of cellular repair processes such as autophagy,” she describes. “By promoting ketone production, fasting provides an alternative energy source for the brain, which may enhance cognitive function and protect against neurodegenerative diseases.”3

Finally, fasting triggers cellular stress responses, and these responses “activate adaptive pathways, increasing neuronal resilience and improving overall brain health,” Dr. Dayananda explains.6

Fasting and Mental Disorders

It’s clear that fasting can be helpful for certain folks in terms of improving mood and boosting cognition, but can it improve specific mental health disorders?

This is also an area where research is still new and not entirely conclusive. Ozan Toy, MD, psychiatrist and chief medical Officer at Telapsychiatry, says that fasting definitely has specific mental health benefits and may be able to improve some of the symptoms of mental health issues such as anxiety, stress, mood, and cognition in some individuals.

Indeed, a 2021 systematic review and meta-analysis found that fasting could relieve some of the symptoms of anxiety and depression, but the study researchers warned that there were several caveats to keep in mind, including that the studies were only preliminary and that no studies were conducted specifically in psychiatric populations.3

As Dr. Feldman notes, there’s been research on the practice of fasting during Ramadan, a religious Muslim holiday marked by a month of fasting. A 2023 study linked Ramadan fasting to reduced interpersonal sensitivity and phobic anxiety, for example. However it is also important to note that some research has found that fasting during Ramadan was associated with a higher recurrence rate in patients with bipolar disorder.7

Again, though, at this time fasting is not prescribed by doctors or psychiatrists as a method of addressing mental health disorders like phobias, anxiety, depression, or any other mood disturbances.

Practical Tips for Safely Fasting

While fasting isn’t for everyone—and anyone who is interested in trying it should check with a healthcare professional first—it does show some promise in terms of helping with mood, mental clarity, and emotional well being for some people.

Getting started with fasting can feel confusing and overwhelming, which is another reason why it makes sense to seek guidance from a healthcare professional or dietician before trying it. It’s important that you stay hydrated while fasting and that you stop immediately if you show signs of disorientation, confusion, feelings of dizziness, faintness or the new onset of any physical or mental symptoms.1

Dr. Dayananda shared her top tips for newbies starting to fast:

• Start slow, trying gradual restrictions and fasting/eating windows
• Once you get the hang of it, try to stay consistent in terms of the windows you choose
• Pay attention to what you eat in your eating window, focusing on nutrient-rich food that will sustain and energize you
• Be patient with yourself as you transition toward longer fasting windows
• Remember that it takes time for the body to adapt
• Keep in mind that everyone is different and it’s up to each of us to decide what works best for our body, in terms of how long to fast, what type of fasting to try, and whether to continue fasting at all

Risks of Fasting

While fasting—especially the less extreme version of fasting, such as intermittent fasting—is generally safe, it’s not for everyone.

“People with certain medical conditions such as diabetes could run into problems associated with hypoglycemia that could have serious consequences,” Dr. Toy says. “Furthermore if someone is suffering from an eating disorder, fasting could also be a risky intervention in this patient population as well.”1

Dr. Dayananda doesn’t recommend fasting to certain groups, like pregnant women and children. “Pregnant women, for example, need to be selective and thorough about their nutritional needs as they eat and drink for two,” she says. “Asking them to fast while pregnant could be uncomfortable or, at worst, dangerous, and therefore not worth the risk.”1

Additionally, as Dr. Feldman emphasizes, anyone experiencing an acute mental health crisis should not turn to fasting as a solution. “Fasting without proper guidance or consideration of one’s health status can result in dehydration, nutrient deficiencies, worsening of mental health symptoms, and disrupted sleep patterns,” he says.

The Bottom Line

While it’s clear that fasting has several potential health benefits, including lowered glucose, blood pressure, cholesterol, and the ability to help maintain a healthy weight, it’s less clear how it impacts mental health.1

There is some preliminary evidence that fasting can improve mood, enhance mental clarity, lower stress, reduce symptoms of anxiety and depression. But we are not at a place yet where mental health professionals are recommending fasting as a treatment for mental health issues.2

At the same time, many people have found fasting to be beneficial for their mental health and overall well being. For most of us, there’s no harm in trying fasting, especially if eased into gradually, with a focus on nutrient dense food during eating windows. Still, pregnant folks, children, people with a history of eating disorders, and people with certain underlying medical conditions shouldn’t fast.1

If you have questions about whether fasting is right for you, don’t hesitate to reach out to your healthcare provider.