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    Want better focus? Healthy cognition as you age? Or maybe just a better chess game? Then brain health is probably on your agenda.

    Brainpower on your wishlist? Explore the connection between intermittent fasting and cognitive fitness. Your focus game is about to level up!

    Aside from cool sci-fi scenarios with a magic pill or technological plug-in that makes you a genius, how else can you improve and/or preserve your brain health?

    Some promising research suggests that intermittent fasting can help you be healthier and happier, not just physically but mentally capable, well into old age. 

    In this article, we’ll explore the science behind intermittent fasting for brain health.  

    Key takeaways

    • Generally, brain health requires overall body health. So, starting with basic healthy behaviors is a foundation for cognitive well-being.
    • Fasting stimulates physiological changes that may benefit brain health in particular.
    • Some people report better mood and focus when fasting, but folks vary in how they feel. Experiment and see what you notice for yourself.
    • While fasting can be part of an overall healthy lifestyle, if you have a known cognitive or neurological condition, always consult your healthcare provider before making any changes.

    Ready for a brain health boost? Take the SIMPLE quiz to gain access to a personalized fasting routine, insightful nutrition scores, and a supportive community. Your brain and wellness journey starts here!

    The metabolic switch of fasting

    To understand whether fasting can support brain health, it helps to understand how fasting works in the body.

    There are many types of intermittent fasting. For more on types of fasting, please check out our article.

    However, they all generally share a process that scientists informally call “flipping the metabolic switch.”[1] This occurs somewhere around 8–12 hours after your last meal, depending on several factors. 

    With this switch, your body shifts from primarily using carbohydrate-based glycogen for energy to using stored fat from your fat tissues. This stored fat gets turned into substances called free fatty acids and then into ketones

    Thus, you might know this state as being in ketosis.

    Want to see your metabolic switch flip in real time? You can see when your body switches to “fat-burning mode” by checking the Metabolic Status indicator in the SIMPLE app while fasting.

    Your brain on ketosis: how fasting changes your brain

    Unlock the power of your mind with intermittent fasting! Embrace the beach vibes, stretch it out, and let your brain revel in the benefits of fasting.

    Why does the body do this metabolic switch into ketosis? Short answer: your brain.

    Your brain isn’t that big — about 2% of your body size — but it needs a lot of energy to run relative to its size: about 20%–25% of your total daily calorie needs.[2,3] (Hey, being a genius takes fuel!)

    Famines and food shortages were common for most of human history. Our brains needed to come up with a way to get fuel when food was scarce. Being smart, of course, it did: ketosis.

    Ketosis occurs when our body makes ketones, or ketoacids, from fats or proteins. Ketones can provide energy when other fuels aren’t available. 

    During fasting, ketones made from stored body fat become the brain’s preferred energy source. Not only do they provide energy, but they may also help regulate important factors in the brain.

    Boosting neuroplasticity with BDNF

    Two key players are BHB (β-hydroxybutyrate) and AcAc (acetoacetate). These ketones are made in your liver during fasting and are sent to your brain. In animal studies, they seem to boost brain-derived neurotrophic factors (BDNF).[4] 

    BDNF helps create new brain cells, strengthens connections between them, and makes your brain more resilient to stress.

    (By the way, BDNF is also stimulated by exercise. So perhaps a morning fasted walk might be a nice little brain boost!)

    However, the research in humans isn’t as strong right now. The results vary, with some studies showing that fasting reduces BDNF.[5] Other factors like measurement methods, sex, and health status play a role. 

    So, we need more human research to draw some better conclusions. But animal studies look promising.

    Fasting and autophagy

    Intermittent fasting also helps your brain through a process called autophagy.

    Autophagy is the process your body uses to break down and clear out damaged cells to make space for new ones. In the brain, this can mean tidying up damaged cells and cellular waste products.

    Brief periods of fasting enhance the activity of genes linked to autophagy.[6] This suggests that intermittent fasting could potentially have a positive impact on autophagic activity. But since we don’t currently have a good way to measure autophagy in humans,  we still can’t say for sure.

    While good housekeeping is important in general, it’s likely especially important as we age. Just as some of us tend to accumulate clutter in our homes as we get older and acquire more “stuff,” our brains can do the same, building up cellular “gunk” that may diminish cognition or contribute to neurodegeneration.

    So, fasting may also be part of healthy brain aging.

    Fasting and neurodegeneration

    Fasting is being explored as part of the treatment or prevention of many neurodegenerative diseases (i.e., diseases where brain or nervous system tissues break down or don’t work as well) due to its potential for enabling ketosis, among other physiological processes.[4,7]

    For instance, evidence from research on Alzheimer’s disease suggests that fasting may help reduce the buildup of harmful brain plaques and slow down memory loss. 

    Although we’re not entirely sure why this works, some think it’s because intermittent fasting could activate pathways that make brain cells tougher and fight inflammation.[7] However, research in this area is still in its infancy, so it’s too soon to explain exactly how this works.

    For Parkinson’s disease, intermittent fasting might offer some protection, too. 

    Some smaller studies have shown promising results with Parkinson’s patients on ketogenic diets, but we need much more research to say for sure.[8]

    Fasting and insulin

    High circulating insulin levels — which can lead to insulin resistance, a situation where cells can’t effectively respond to the signal of insulin — are increasingly linked to worse brain health.[9]

    By lowering circulating insulin, fasting may help alleviate this and indirectly support brain health.[10] Exercise also helps support insulin sensitivity in the brain, so there’s one more vote for those nice little fasted strolls![11–13]

    If you’re ready to give intermittent fasting a try, take our SIMPLE quiz and start your fasting journey!

    Will fasting make you smarter?

    While there’s interesting evidence (mainly from animal studies) that fasting may slow neurodegenerative processes, it’s not clear whether it reliably boosts cognitive function in humans, especially neurotypical people (i.e., people with no diagnosed cognitive conditions or neurological variations).[14]

    However, many people report feeling “sharper” when fasting. 

    This is likely due to the release of catecholamine hormones such as adrenaline (epinephrine) and noradrenaline (norepinephrine), which are linked to alertness and focus.[15] 

    On the other hand, other people report feeling “brain fog” with less focus and concentration.

    Likely, there are individual variations in how fasting affects people’s cognitive performance, focus, and concentration. 

    Take-home: Experiment and notice how you feel when you fast. 

    • Do you feel more alert and focused? If so, then fasting may be a good fit for times when you need more mental horsepower.
    • Do you feel fuzzy and foggy? If so, then perhaps time your fast, so you aren’t doing anything important during that period.

    Will fasting make you happier?

    Cheers to feeling fantastic! Explore the happiness boost of intermittent fasting. Lift your glass, enjoy the journey, and let the positive vibes flow.

    What’s good for your brain (and the rest of your body) is good for your emotions, and intermittent fasting may also play a positive role here. 

    Many people report feeling more energetic and positive while fasting.[15] In part, this may reflect the effects of dopamine, a neurotransmitter (brain chemical) involved in getting us motivated to seek rewards. 

    In our evolutionary past, hunger motivated us to leave the safety of our burrows and go find food. The dopamine system is part of helping us take risks and get moving.[16] For some people, this activation of dopamine and surge of activity may help alleviate symptoms of depression.[17,18]

    There’s also emerging evidence that fasting may play a role in helping alleviate some types of chronic pain, likely by working through some similar mechanisms, but research is in its infancy, and we look forward to seeing what may come out of this.[19,20]

    Take-home: Try fasting out for yourself and observe how you feel during your fasts. Do you feel better? If so, great!

    SIMPLE’s expert opinion and final thoughts

    Body health contributes to brain health. So, all the healthy behaviors that support a healthy body also support a healthy brain. 

    Notice how you feel and function while fasting. If you feel sharper, clearer, and more alert, that’s a great sign. If you feel fuzzier and more foolish, and it never improves, try adjusting your fasting window or exploring other approaches.

    Try to cover all your brain health bases. Along with fasting, you can promote brain health with other healthy choices like:

    • good nutrition, especially omega-3s, antioxidants, B vitamins, and minerals, including magnesium and zinc from a range of whole grains, fruits, vegetables, and lean proteins[21]
    • regular exercise (at least 20 minutes a day of walking and some strength training is great)[22]
    • good sleep[23]
    • stress management[24]
    • time outside in nature[25]
    • strong and supportive relationships[26]

    Make sure fasting is right for you. While fasting can be part of an overall healthy lifestyle, if you have a known cognitive or neurological condition, always consult your healthcare provider before making any changes. 

    We also don’t recommend fasting for people who:

    • have type 1 diabetes
    • are currently pregnant or breastfeeding
    • are younger than 18 or 80 and older
    • are on certain medications, including ones for blood pressure or blood sugar lowering
    • have an eating disorder or disordered eating tendencies (or have a history of one)
    • have a BMI lower than 18.5

    Frequently asked questions about fasting and brain health

    In general, fasting can be safe and even beneficial for the brain when done correctly.

    However, it’s essential to stay well-hydrated while fasting and ensure you’re getting proper nutrition during eating periods. If you have underlying health conditions or concerns, consult a healthcare provider before starting a fasting regimen.

    Fasting might improve mental clarity and focus for some individuals. When your body starts using ketones for energy, it can lead to enhanced cognitive performance.[7]

    Some people report feeling sharper and more focused during fasting periods, while others say they feel less focused and more fuzzy. Experiment and see what works for you, and time your fasts accordingly.

    While there’s exciting research on fasting and its potential benefits for neurological conditions, it’s based on animal studies and, therefore, still in its infancy.[14] It’s essential to work with a medical professional to explore appropriate treatment options tailored to your specific condition.

    The duration of fasting required to see benefits can vary from person to person. You can expect to see results from intermittent fasting in as little as a few weeks.[27]. The key is consistency, so find a fasting routine that works for you.

    Fasting may not be suitable for everyone, especially individuals with certain medical conditions or those who are pregnant or breastfeeding. There’s also a risk of nutrient deficiencies if you’re not careful about what you eat during non-fasting periods.

    We always recommend that you speak with your healthcare provider. Also, just a friendly reminder that any information from this article isn’t meant to replace existing medical advice.

    Not everyone’s body responds the same way to fasting, so feel free to experiment and find what works best for your body and lifestyle. Get started with our SIMPLE quiz, and we’ll help get you on the right path.

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