Limidax™ XR
Intermittent Fasting Effects on Your Brain: Can It Boost Cognitive Performance?

Orange cooking time on the floor drawing fasting cognitive performance

Intermittent Fasting Effects on Your Brain: Can It Boost Cognitive Performance?

People decide to fast for a number of reasons. Some want to reduce their weight, some want to attain a higher level of focus, and some still might do it for religious reasons. No matter the reason, fasting can have a profound effect on the body and specifically the brain. Intermittent fasting is a particularly effective way for people to increase their health as well as their brain power.

What is Intermittent Fasting?

Intermittent fasting, or IF for short, is more than a diet plan. It’s a lifestyle. Here’s how it works: you have a set window of time each day that you are able to eat. Outside of that window, you are allowed only water, green tea, black tea, and black coffee. You are able to determine the confines of your own fasting system. You choose how long your window is and when it occurs during the day. If your window is longer than about 8 hours, then it isn’t really considered intermittent fasting, since that amount of time allows for the dieter to conform to the traditional eating times.

How to Practice Intermittent Fasting

The best way to practice Intermittent fasting safely and effectively is to choose a window in which you could eat about 2 meals. For many, an ideal window is 5 or 6 hours to allow for digestion in between meals. It’s important to remember that while practicing IF, the number of calories per day is not usually reduced. That’s what makes it different than a traditional diet plan. This is the part that poses a problem for many wanting to try IF. Needing to fit around 2,000 calories in during only a few hours can actually be quite challenging. Sure, it would be easy to go to any fast food restaurant and eat one meal to get nearly all of your required calories for the day. But then you wouldn’t be doing your body, or your mind, any favors. The meals or snacks you eat while fasting should be full of complex carbohydrates, fiber, lean protein, and lots of fruits and vegetables.



Fasting need not be done every day to be considered IF. After all, that is the nature of Intermittent fasting: it’s occasional, recurrent, and structured, but not necessarily every day. One plan, made popular by BBC’s Michael Mosley on Horizon: Eat, Fast, and Live Longer, is the 5:2 Diet plan. During this IF plan, the dieter chooses 2 days on which to fast, and 7 days to eat regularly, but healthily. During the 2 fasting days, only ¼ of regular caloric intake is eaten (600 calories or less). A third option is Alternate Day Fasting, or ADF. This works exactly as it sounds: one day is spent eating regularly, while the following day is spent in fast. This can be tough to stick to, since the time between meals can stretch to 36 hours, including sleeping.

Concerns During Intermittent Fasting

The largest concern while fasting is water intake. It’s actually surprising how much of our daily water intake comes from our food. So, if food is being taken in less often, there is a big chance that dehydration could occur. If you choose to do Intermittent fasting, remember that drinking water, tea, and coffee frequently is a necessity. Despite the change in diet plan, if you are consuming enough liquids spaced throughout the day, your brain can continue to work at optimal levels. If dehydration occurs, your body and mind will begin to feel slow and sluggish- you’ll have less energy, your focus will decrease, and you could even get headaches. And that’s the opposite of the desired effects of IF!

Additionally, if you have any preexisting medical conditions, fasting might not be the best idea. Conditions such a hypoglycemia and diabetes can pose a large risk when fasting because of the effects on insulin levels in the blood. If you have a high-stress lifestyle and have been diagnosed with adrenal fatigue, you should also avoid fasting, as it can make the condition worse. Finally, pregnant and nursing mothers should not fast. Even intermittent fasting can deprive your baby and yourself of much-needed nutrients. No matter your health, you should always undertake a fast with the approval and supervision of your doctor.


Biological Impact of Intermittent Fasting

If you’ve ever gone for a long period of time without eating any food, then you know the profound impact that hunger and going without fuel can have on the body. But beyond the discomfort associated with fasting, what happens at a biological level in the body? Since the body isn’t receiving any new fuel, it decides to make the best of the existing cells by pruning out anything that isn’t healthy. This is what Michael Mosley referred to as “the switch from ‘growth mode’ to ‘repair mode.’” This has several effects:

  • Insulin levels are decreased dramatically. Since there is no food intake, the body doesn’t signal for any insulin to be excreted into the blood. During IF, the body essentially resets and learns to better control insulin and work without it, resulting in the body burning fat for fuel instead of sugar. This has been shown in studies to reduce the risk of certain chronic diseases, like cardiovascular disease, aging, and even cancer.
  • The body instead makes more Human Growth Hormone. This hormone helps to release fatty acids into the bloodstream to be used for energy, which results in fat stores decreasing with little to no crash in energy levels.
  • Hormone Sensitive Lipase, which is responsible for telling the body to use stored fat for energy when needed, is also excreted during IF.  But since it’s sensitive to insulin, it can’t work properly unless no sugar is being consumed.

blood brain barrier

What Intermittent Fasting Does to the Brain

The effects of Intermittent fasting aren’t just limited to the body. The brain can reap big rewards as well. This is due to the rise in a biochemical than increases the growth of new neurological tissue, called brain-derived neurotrophic factor, or BDNF. Fasting is what IF researcher Dr. Mark Mattson calls a “cognitive challenge.” Our brain responds to this challenge by increasing BDNF levels, which in turn results in new neurons created from brain stem cells. Having new and healthy neurons, as well as new and strengthened synapses, can result in improved memory and learning ability. Further, BDNF helps keep brain cells from deterioration and aging, which can fight off Alzheimer’s and Parkinson’s disease. It also keeps the brain sharp through the aging process. Fasting provides the brain with ketones from burning fat, which is the brain’s preferred fuel source. Burning the preferred ketones will aid in keeping the mind focused and will most definitely increase energy. With the combined efforts of the BDNF and ketones, the body is able to have optimal neural performance from the sustained energy and the improved growth and maintenance of neural tissues.


Intermittent fasting is not for everyone. It’s a challenge, both on a physical and mental level. If practiced properly, the body can see great improvement. It can create a leaner physique and have a positive impact on biomarkers for disease. Most importantly, it can give the brain a big cognitive performance boost. It will create an environment in which brain tissues can grow, strengthen, and flourish. The result is better memory, increased attention and focus, and faster learning. As with any diet plan, IF should be carried out under a physician’s supervision to ensure safety.

About the Author

Limidax Team

The Limidax Team includes neuroscientists, researchers, and health coaches. We hope you find these articles useful. If you have any questions at all, always feel free to reach out to us.