Many people swear that fasting—meaning not consuming anything but typically water, coffee or tea for a period of about 14 to 18 hours (or sometimes longer)—is one of the best ways to boost productivity, gain mental clarity and even break unhealthy habits. It’s not surprising then that intermittent fasting has emerged in recent years as one of the most used dietary strategies for supporting mental/cognitive health.

Intermittent fasting is another term for “time-restricted eating,” in which you eat only within a certain “eating window.” Researchers believe that intermittent fasting benefits both our brains and bodies in several ways:

  • The physiological effects of voluntary fasting actually mimic those of starvation. Both intermittent fasting and food deprivation are considered types of “positive stressors,” just like exercise is. They cause the body to adapt in ways that promote health and fight disease, such as by reducing inflammation, improving detoxification and enhancing cellular renewal.
  • Fasting has been shown to have anti-aging effects in the human brain. It can help improve neuroplasticity (the brain’s ability to form new neural connections) and fight inflammation, which correlates to better memory, not to mention improved capacity to learn and retain new information.
  • Some studies have found that fasting can help support recovery from brain injuries and strokes and lower the risk for developing neurodegenerative diseases like Alzheimer’s, dementia and Parkinson’s disease.
  • Aside from its ability to boost mental health, fasting also can help with mood enhancement, weight loss/management, prevention of diabetes, growth of muscle mass and much more.

Editor’s Note: Consult your health care practitioner before you make any changes in your diet or exercise regimen.

How should you get started with intermittent fasting?

There are a number of different ways you can practice intermittent fasting, but those described below are the most popular and often the most realistic and sustainable.

  • Stick to an “eating window” of about four to eight hours per day, which means you should consume all meals within this time frame and fast over the remaining hours (which usually includes an overnight fast). As an example, you might only eat from about 2 p.m. to 6 p.m. or 8 p.m. on days that you’re fasting.
  • If a four- to eight-hour eating window seems a bit too tough, especially when you first get started, then begin with an eight- to 10-hour eating window instead as your body acclimates to fasting.
  • When you’re fasting, avoid eating any solid food at all (or smoothies, shakes, juices, etc.,), but you can still consume sugar-free coffee, tea, seltzer, or water infused with lemon juice or essential oils.
  • Many people who practice intermittent fasting do so by skipping breakfast. This strategy has pros and cons. For example, consuming food earlier in the day and avoiding eating at night seems to be very beneficial for metabolic health in general, according to recent studies. However, if you like to eat dinner with your family or have flexibility in your schedule to go out with friends later in the day, then skipping breakfast in order to fast will be a more realistic option.
  • Yet another approach is to do alternate-day fasting, in which you consume about 500 calories or less on fasting days and then eat normally and focus on food quality on non-fasting days.

If you’re willing to give a low-carb diet a shot, you may want to experiment with combining fasting and the ketogenic diet—a high-fat, low-carb diet that has many therapeutic effects, including for enhanced cognitive performance.

The keto diet puts the body into a state of ketosis,  in which the body is burning fat instead of carbs for energy. Once someone is in ketosis, they produce molecules called ketone bodies, which studies have shown can help reduce inflammation in the brain, increase mental clarity, improve your mood, decrease pain, reduce cravings and improve physical performance.

What should you eat when you’re not fasting if you want to feel your best?

While fasting itself offers many benefits, it’s still important to focus on quality nutrition when you’re inside your eating window.

The brain is the most energy-consuming organ in the human body, so it makes sense that your diet will help determine how you feel mentally and emotionally. If you’re low in essential nutrients (and also calories), then you’re not going to be performing cognitively as well as you could. Researchers now believe that a poor diet is a major contributing factor to mental health issues, including depression and anxiety, not to mention that it can increase your risk for cognitive decline as you age.

In the newly emerging field of “nutritional psychiatry,” researchers have been uncovering much more about the impact that nutrition has on the brain and mental health. A March 2019 article published by The New York Times reports that “nutritional psychiatrists counsel patients on how better eating may be another tool in helping to ease depression and anxiety and may lead to better mental health.”

When you aren’t fasting, focus on including these food groups in your diet in order to support brain health:

  • Fresh fruits and vegetables. Consuming a wide array of colorful fruits and vegetables like peppers, blueberries, sweet potatoes, dark leafy greens like spinach or kale, carrots, tomatoes and so on is the best way to obtain antioxidants and phytonutrients that reduce harmful inflammation throughout the body, including the brain. Aim to have about 1½ to 2 cups per day of fruit and 2 to 3 cups per day of vegetables.
  • Foods that are rich in vitamin B12. Vitamin B12 is energy-promoting and may even help to reduce brain shrinkage. Good sources include grass-fed beef, eggs, wild-caught fish, organ meats like liver and nutritional yeast.
  • Foods that supply omega-3 fatty acids. Omega-3 deficiency has been linked to higher risk for depression, obesity and many other conditions. Omega-3 fats (and other healthy fats like nuts, seeds and olive oil) are imperative for cognitive function and can be found in foods like salmon, halibut, sardines, tuna, walnuts and flaxseeds.

In addition to emphasizing the foods above, work on cutting out processed foods made with sugar, processed vegetable oils and refined grains; minimize poor-quality meat and dairy; and reduce your consumption of alcohol and caffeine. It’s also very beneficial for your stress levels and overall well-being to practice “mindful/intuitive eating,” which means slowing down when you eat, becoming more aware of your thoughts about food and your body, and noticing how you feel when you eat heathy, whole foods versus processed foods.

Overall, research tells us that when it comes to feeling our best emotionally for many years to come, we should aim to follow a balanced Mediterranean-style diet, which you can do whether you also choose to do intermittent fasting or not.

Studies show that among people who follow a diet similar to the Mediterranean-style diet, their brains remain sharper into older age and have larger volumes compared to people who eat a more typical Western diet. A Mediterranean diet (also referred to as the MIND diet) includes whole foods like fatty fish, a variety of vegetables, whole grains, legumes, nuts, seeds and olive oil—all of which are great for your mood, mental performance, waistline and overall health.

Dr. Josh Axe, DC, DNM, CNS, is a doctor of chiropractic, doctor of natural medicine, clinical nutritionist and author with a passion to help people get well using food as medicine. He operates the No. 1 natural health website in the world at, with more than 15 million unique visitors every month, and is co-founder of Ancient Nutrition, a health company that provides history’s healthiest whole-food nutrients to the modern world. He’s author of the books “Eat Dirt,” “Essential Oils: Ancient Medicine” and the just released “Keto Diet: Your 30-Day Plan to Lose Weight, Balance Hormones, Boost Brain Health, and Reverse Disease.”

Photo credit: Ella Olsson, Unsplash