Does intermittent fasting affect your brain?

Intermittent fasting (IF) – not to be confused with caloric restriction, which extends longevity in animals and might do the same in humans – is only one of the many ways of “lifestyle-eating” popular right now. But did you know that it’s not new? Many religions incorporate some form of intermittent fasting, though often for reasons (lack of food or spiritual pursuits) other than the ones we see today, such as losing weight, fighting inflammation and reducing insulin resistance. Maybe there’s a reason why most of the world’s major religions call for periodic fasting. So, what is intermittent fasting? 

Many definitions
While there are many definitions, the simple answer is restricting the number of hours you eat in a day or closing your feeding window. I have practiced this for quite some time and have seen some great results, especially when it comes to keeping weight off. I find that intermittent fasting clears my mind, enhances my senses and improves brain functioning. I strive to eat dinner no later than 19.00 (not always possible) and then eat my first meal the next day no earlier than 12-13.00. The number of hours people fast varies from 12 to 20 hours, and some fast every other day. But a new study from Singapore has revealed surprising results – intermittent fasting for 16 hours promotes neurogenesis and helps combat dementia. 

Neurogenesis
Neurogenesis is the process by which new neurons are formed in the brain. The Singapore study, which was conducted on rats and published in Brain and Behavior, wanted to find out if intermittent fasting affected neurogenesis and, if so, how? The study took a close look at the brain’s hippocampus (responsible for consolidating short-and long-term memories), which is most often the first part of the brain affected by Alzheimer’s disease. It’s possible to create new neurons throughout your life. According to the study, the more neurons you create as you get older, the less likely you are to develop dementia. The study tested four groups of rats – three which fasted for 12, 16 and 24 hours, respectively – and a fourth that didn’t restrict eating at all. While all three time-restricted groups showed better hippocampal neurogenesis than the control group, the results revealed that the group that fasted for 16 hours performed best. So, what’s the take-away from this experiment? As far as cognitive health is concerned, it’s when you eat that matters most. If you restrict your feeding window to eight hours a day, you’re likely to have significant effects. But wait, there’s more!

Additional benefits
Other researchers have written about the positive effects of intermittent fasting on the heart, immune system, liver and the body’s ability to fight cancer. The Singapore research team says: “Prophylactic IF has been shown to promote longevity as well as ameliorate the development and manifestation of age‐related diseases such as cardiovascular, neurodegenerative, and metabolic diseases in many animal studies. It has also been postulated that IF can cause changes in the metabolic pathways in the brain, which leads to stress resistance capacity of brain cells.” In other words, you stand to benefit in many ways when restricting your feeding window. Intermittent fasting fuels your brain’s natural growth factors and supports the survival and growth of neurons. It also promotes metabolic switching. The dictionary defines metabolic switching as “using fasting to transition the body from a state of fat storage to one of fatty acid release and oxidation.” Moreover, “metabolic switching impacts multiple signaling pathways that promote neuroplasticity and resistance of the brain to injury and disease, according to Nature Reviews Neuroscience.” But does intermittent fasting make you smarter?

Fact versus hyperbole
I think many of us get confused by fasting trends, wondering how much is overinflated buzz and hyperbole and how much is fact. Any of the previously mentioned metabolic changes that take place during fasting generally end when the fast does. And most of us can’t live in a perpetual state of fasting. It’s just not sustainable. Enter intermittent fasting again. Mark Mattson, head of the Laboratory of Neurosciences at the National Institute on Aging Intramural Research Program, claims he hasn’t eaten breakfast in 35 years and only consumes 2,000 calories daily in his six-hour feeding window. Mattson and his team also studied mice (surprise, surprise). He divided the mice into two groups and fed each group the same number of calories throughout the study. One group fasted every other day and the other ate as they usually did. The group that fasted showed a 50 percent increase in brain-derived neurotrophic factor (BDNF), a protein that works like fertilizer to promote new neuronal connections. Of course, it remains to be seen ff what works for mice will work for men, but it does seem promising.