Fasting: Part of a Good and Healthy Brain Diet

Sana U. Khan, MD, PhD

When discussing brain health and nutrition, one’s mind often starts thinking about fruits, vegetables, dietary supplements, vitamins, proteins, etc. Rarely does one consider intermittent fasting as a potentially valuable part of brain nutrition. Well, let’s look into some medical benefits of why fasting should be part of a good and healthy brain diet.

In a process called “metabolic switching,” fasting actually triggers a shift in the resources your body uses for energy. The process of metabolic switching allows the body time to first use stored glucose in the liver, and then utilize fatty acids and ketone bodies for energy. This triggers a biological cascade in the body which scientists believe may build the brain’s resilience and productivity, as well as boost its support system. Metabolic switching between glucose and ketones is when cognition is best and degenerative diseases are kept at bay. As a recent paper in Nature Reviews Neuroscience put it: “Metabolic switching impacts multiple signaling pathways that promote neuroplasticity and resistance of the brain to injury and disease.”

Fasting for extended periods may also help generate new brain cells. Studies have shown that when groups of mice were deprived of food every other day for windows of between 12 and 16 hours, they had higher levels of specific protein markers compared to mice that were not deprived. These markers indicate new brain cells were being made, suggesting the fasting mice may have been making new brain cells more efficiently and at a faster rate than the control mice.

Interestingly, fasting boosts a chemical called Brain Derived Neurotrophic Factor (BDNF) that can help make your neurons more resistant to stress.  Research in the Journal of Nutrition Health & Aging found that after three months of intermittent fasting, study participants reported improved moods and decreased tension, anger, and confusion. Another study from 2018 investigating weight-loss strategies found intermittent fasting was associated with significant improvements in emotional well-being and depression. “One thing we found pretty recently, that may explain the ability of intermittent fasting to reduce levels of anxiety and also protect against a number of neurological disorders, is that intermittent fasting will enhance the ability of nerve cell networks to control their activities and electrochemical activity,” says Mark Mattson, head of the National Institute on Aging’s neuroscience laboratory.

Avoiding high blood sugar levels in our bodies is beneficial for many reasons. Research in the British Journal of Nutrition shows that intermittent fasting produces greater improvements in insulin sensitivity, which helps you prevent high blood-sugar levels and type 2 diabetes. The journal Neurology has published findings showing high blood sugar is associated with a smaller hippocampus, the seahorse-shaped structure in your temporal lobes associated with mood, learning, and memory.

Studies have also shown that anxiety and depression are two to three times higher in patients with type 2 diabetes than in the general population. Dr. Mattson noted that mice who fasted regularly were healthier by some measures than mice subjected to continuous calorie restriction; they had lower levels of insulin and glucose in their blood, which signified increased sensitivity to insulin and a reduced risk of diabetes.

Scientists at the Buck Institute for Research on Aging have shown how fasting benefits the brain on a neurological level. Within only a few hours, dietary restriction triggered a response from molecular pathways that govern synaptic activity, or neurotransmitter release. By reducing the release of neurotransmitters from synapses in the brain, fasting may also give the nervous system a break. Neuroscientists have linked overactive synaptic activity with neurodegenerative diseases such as Alzheimer’s, Huntington’s and Parkinson’s disease, and therefore fasting could be an effective preventative measure. “We believe that tuning of synaptic activity as a result of acute fasting might be beneficial for people who are at high risk for neurodegeneration,” says Dr. Pejmun Haghighi, a professor at the Buck Institute.

Fasting helps remove damaged mitochondria, the powerhouses of our cells, in a process called autophagy.  This can lead to improved energy pathways and give us that extra boost in energy and brain power! Essentially, autophagy is the process by which your brain “takes out the trash” that builds up during the day. This self-cleaning process helps detoxify the brain, clear out old and damaged cells, and sweep away debris. This nightly housekeeping promotes the regeneration of newer, healthier cells. A wealth of research has shown that problems with autophagy have been linked to Alzheimer’s disease, depression, bipolar disorder, schizophrenia, and other neuropsychiatric disorders.

Fasting boosts brain function and can improve learning efficiency. Restricting the hours when you eat has been shown to significantly improve memory, according to a study in the Journal of the Academy of Nutrition and Dietetics. In this study, after four weeks of intermittent fasting, performance on a spatial planning and working memory task and on a working memory capacity test increased significantly. Additional research on animals has found intermittent fasting improves learning and memory.

Fasting also leads to reduction in the body’s internal inflammation. Chronic inflammation has been linked to many brain disorders, including depression, bipolar disorder, obsessive compulsive disorder (OCD), schizophrenia, Alzheimer’s disease, and more. According to a study in Nutrition Research, intermittent fasting decreases inflammation, which can have potent benefits for your brain health and mental well-being.

Intermittent fasting helps reduce blood pressure which is beneficial for the heart, and anything that’s good for your heart is also good for your brain. Having hypertension or pre-hypertension lowers blood flow to the brain. Low blood flow on brain imaging scans has been seen with depression, bipolar disorder, schizophrenia, ADD/ADHD, traumatic brain injury, substance abuse, suicidal thoughts, and more. In addition, low blood flow is the #1 brain imaging predictor that a person will develop Alzheimer’s disease.

While these are some of the benefits of fasting for our brain’s health, they are certainly not all.  As research in the area of brain nutrition grows, we will certainly continue to learn how to eat better to improve our brain functions and perhaps how not to eat to accomplish the same.

Dr. Sana Khan is an accomplished radiologist, researcher, teacher, and entrepreneur. He was the first radiologist in the United States with the Stand-Up Weight-Bearing MRI and has contributed significantly to the advancement of this technology. He is a nationally- renowned scientist conducting ongoing research with the Departments of Orthopedic Surgery at UCLA, USC, UCSD, and the US Department of Defense. Having developed state-of-the-art MRI techniques, Dr. Khan brings extensive expertise in the medical-legal aspect of imaging musculoskeletal and traumatic brain injuries. www.expertmri.com