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    Over the past several years, taking regularly scheduled breaks from eating — in other words, intermittent fasting — has become something of a phenomenon. But does intermittent fasting really live up to the hype? 

    The buzz around intermittent fasting is real, but so are the health benefits. At SIMPLE, we unravel the science to reveal how intermittent fasting empowers a vibrant, healthy lifestyle.

    Is fasting really good for your health, or is it an unhealthy option in the long term?

    In this article, we’ll explore the possible health benefits and risks of intermittent fasting to help you decide if intermittent fasting might be part of your health routine.

    Key takeaways

    • Intermittent fasting is linked to many health benefits — although many of those benefits might also result from weight loss or better nutritional choices.
    • While intermittent fasting will likely help support and improve your health if you’re starting from a base of less-than-stellar lifestyle habits, it will not make you super duper extra healthy if you’re already healthy and doing key lifestyle behaviors consistently.
    • For most people, intermittent fasting is safe enough to try. You can track your own health indicators to see whether it makes a difference. 

    If you’re new to intermittent fasting, check out our guide on intermittent fasting for beginners and see which of the methods we share might suit you. If you need a little more help deciding your best approach, try our SIMPLE quiz.

    Why does intermittent fasting benefit your health?

    We know there are many health benefits of intermittent fasting.[1] (More on this in a moment.) 

    Yet, it can sometimes be hard to tell whether they are due to:

    • losing weight, which occurs for many people when intermittent fasting;[2]
    • more awareness of physical hunger and fullness cues;
    • making wiser and more mindful eating and nutrition choices
    • eating fewer overall calories, which has been linked to longevity;[3]
    • making other lifestyle improvements, such as getting more exercise along with fasting; or
    • going through the process of fasting itself — for instance, the shifts in metabolic and cellular processes that occur after several hours without food.[4]

    Let’s briefly look at that last item.

    What happens when you fast?

    When you go without eating for around 10 to 14 hours or longer, your body goes through some changes.[5]

    Pro tip: Use the fasting timer in the SIMPLE app to see changes in your body status. Plus, our app is full of resources, recipes, insights, and support to help you reach your goals. Take our SIMPLE quiz to get started!

    First, your body starts using up stored energy in your liver and breaks down fat into free fatty acids (FFAs) in fat cells.

    These FFAs then go to your liver and get turned into substances called ketone bodies, like acetoacetate and β-hydroxybutyrate (β-HB).[6] 

    These are like alternative sources of energy for your body, and they help your body keep going even if you haven’t had food for a while. Researchers think that periodically circulating ketones might have health benefits.[7–9]   

    The FFAs also activate certain cellular messengers that have effects throughout your body. Fasting also encourages your body to make more mitochondria (the energy powerhouses of cells) and makes them work a bit differently.[10–12]

    All of these — and more — are some reasons why fasting might benefit health.

    While this question may be important for scientists to figure out, “regular people” who just want to feel and function a little better can simply enjoy these benefits as they emerge. 

    So, let’s look at what many people can expect to get healthwise from intermittent fasting.

    What are the health benefits of intermittent fasting?

    Fueling the body with nature’s bounty. While she preps these fresh delights, intermittent fasting works its magic on her health from the inside out. Brain, heart, gut — every bit gets a boost!

    Let’s go head to toe! Intermittent fasting has been shown to improve:

    • brain and cognitive health
    • metabolic flexibility
    • blood sugar control and insulin sensitivity
    • cardiovascular health
    • the gut microbiome
    • sleep and circadian rhythm
    • overall cellular cleanup and waste elimination

    If fasting is combined with eating fewer calories overall, people lose weight, which is linked to many health improvements. 

    Let’s look at each of these a little more closely.

    Brain and cognitive health

    Intermittent fasting appears to improve brain function in both the short and long term.[13,14] 

    Thanks to the effect of certain hormones called catecholamines, many people say they feel more alert and focused while fasting. (This isn’t true for everyone, and other people report the opposite of “brain fog.”)

    In the long term, fasting may lower the risk of neurodegeneration (the breakdown of our brain and nervous system tissues) and neuroinflammation (the inflammation of those tissues), both of which are linked to diseases like Alzheimer’s, Parkinson’s, and age-related dementia.[5,15–17] 

    Even more exciting, some studies have shown that mild cognitive impairment can potentially be slowed with calorie restriction and fasting.[5,18,19] Researchers are also exploring whether intermittent fasting might be part of a treatment plan for traumatic brain injury (TBI).[7] .While we need more research in this area, initial results look promising!

    Better blood sugar control and insulin sensitivity

    If your doctor has ever asked you to do a fasting blood test, it’s because even a single fasting interval (usually overnight) can reduce insulin and glucose.

    This is because when we eat foods with carbohydrates, our pancreas releases insulin to help our body store blood sugar (glucose) in our cells. 

    When this is working well, we stay healthy and have readily available fuel and energy when we need it. When it’s not, we might have energy spikes and crashes or consistently high insulin that our cells eventually “tune out” (aka insulin resistance).

    By creating periods of several hours where neither high blood sugar nor insulin is circulating, intermittent fasting helps us manage our blood sugar and improve our insulin sensitivity (i.e., our body’s ability to effectively use insulin to do its job).[20,21] 

    This may not only help lower your risk of type 2 diabetes, but also lower your risk of many other chronic diseases, such as cardiovascular diseases and cancer.[22,23]

    Cardiovascular health

    With every stride under the sun, they’re not just building memories but also heart health. Paired with intermittent fasting, it’s a recipe for happier hearts and lower cholesterol.

    Intermittent fasting may improve markers of cardiovascular health[5,20,21,24], such as:

    • lower LDL cholesterol (aka “bad” cholesterol)
    • lower triglycerides
    • lower blood pressure
    • lower homocysteine levels

    Improved gut microbiome

    The gut microbiome is the collection of friendly bacteria, fungi, and viruses that live in our gastrointestinal tract. These organisms are important for our health. 

    For instance, people who have a lot of body fat often have different types of gut microorganisms than people who are lean, as well as less diversity in those microorganisms. Researchers think that the gut microbiota in people with more body fat might be better at getting extra energy from the food we eat, which can lead to weight gain.[25]

    Obesity can also change the gut microbiota in a way that makes our gut more permeable, meaning things can pass through it more easily. This can lead to inflammation, which is a big problem in obesity.[26]

    However, intermittent fasting may help change our gut microbiota in a good way, which could be good for our health as well as help us lose weight (or manage our weight).[25,27–29] This is especially true if we combine intermittent fasting with a high-fiber diet. However, we need more research to confirm this.

    Sleep and circadian rhythm

    Our bodies have a built-in clock, known as the circadian rhythm, that tells us when to do different things. For example, it tells us when to be active during the day and when to rest at night. 

    This clock is linked to many processes in our body, like hormones, movement, sleep, and overall metabolism.

    Some types of fasting might help optimize how our body clock functions.[30] 

    Fasting schedules that involve eating during the day — and possibly putting most of our eating earlier, such as before late afternoon — while fasting in the evening and overnight might help our body’s clock work better, improving our overall health and how our body handles energy.

    Additionally, eating at night (especially large meals) can lead to indigestion and poor sleep. Many studies have shown that when we eat late at night, we tend to sleep less and not as well.[31,32] 

    Poor sleep contributes to many chronic health problems, such as diabetes, heart problems, mood disorders, and weight gain.[33]

    However, by setting limits on our night-time eating (for instance, having the last meal of the day at 6 PM), intermittent fasting may help support both better sleep and the metabolic benefits of good rest. 

    Overall cellular cleanup and waste elimination

    Fasting may increase autophagy, a process where your cells clean out old and damaged parts. It may also increase apoptosis, programmed cell death where the cells who aren’t stepping up to the plate anymore decide to take themselves out of the game.[34,35]

    It’s worth noting, however, that more research is required in this area to further understand and validate whether intermittent fasting has a key role to play in autophagy and health benefits, particularly in humans.

    Longevity

    Evidence from so-called “Blue Zones,” areas of the world where people live longer — and healthier — than average, suggests that eating just a little less long term might be good for us. In these regions, people either practice “eating to 80% full” or have regular fast days.[36]

    The good news for those of us who enjoy food is that we needn’t eat less at every single meal. Rather, periodic intermittent fasting or fasting-mimicking diets — which means eating less at certain times and eating normally at other times — might just do the trick.[37,38]

    Want to learn more about fasting-mimicking diets and how they match up with intermittent fasting? Check out our article on how intermittent fasting works with other diets

    Health risks of fasting

    While intermittent fasting in general is safe enough for most adults to try, some people should not fast.

    Avoid fasting if you:

    • are pregnant or breastfeeding
    • have a health condition that increases frailty (e.g., undergoing chemotherapy, osteoporosis, etc.)
    • are younger than 18 years of age, or are 80 years old or more
    • need to take medications or have medical treatments that require you to eat
    • have (or are at risk of having) an eating disorder or have a history of one
    • have been told by your doctor not to fast

    Remember that intermittent fasting works best when it’s intermittent — in other words, when it’s a short-term change to your body’s routine.

    SIMPLE’s expert tips and final thoughts

    If you want to improve your health, the evidence from intermittent fasting research is pretty promising.

    Since fasting often also means more mindful eating and awareness of hunger and fullness, combining intermittent fasting with wise nutritional choices and eating what your body really needs is the perfect health-promoting mix.

    Intermittent fasting will likely help support and improve your health, especially if you’re starting from a base of less-than-stellar lifestyle habits.

    Remember to keep the “intermittent” in intermittent fasting — more is not better. 

    For most people, an occasional fast or a daily time-restricted eating pattern of no more than 16–18 hours of fasting is just about right. You won’t get healthier by spending 10 days on a desert island with no food.

    For most people, intermittent fasting is safe enough to try. You can track your own health indicators to see whether it makes a difference. 

    Have fun experimenting!

    Frequently asked questions about intermittent fasting and health

    I have a health condition. Will intermittent fasting help?

    Always discuss your specific situation with your healthcare provider before starting a new eating pattern or making any major changes. 

    Intermittent fasting isn’t a miracle cure. While there are promising benefits, it’s important that you first get the “all-clear” if you have existing health conditions.

    I am taking medication. Is it OK to fast?

    Again, always begin by asking your healthcare provider about any changes to your habits when taking medications

    Many medications should be taken with food or require you to eat regularly.

    See our article on fasting while taking medications to find out even more.

    Is there a healthiest way to do intermittent fasting?

    No. Finding the right intermittent fasting routine for you means considering your own unique lifestyle, daily schedule, preferences, and so on. 

    Not sure which intermittent fasting protocol to choose? We gotcha! Take our SIMPLE quiz, and we can help you figure out the best plan for your unique body, preferences, and lifestyle.

    That said, remember the “intermittent” part of intermittent fasting. Fasting too aggressively, too often, and for too long will likely not improve your health — and may make it worse.

    Balance intermittent fasting with a nutritious diet that helps your body get all the energy and nutrients it needs.

    Try logging your food in the SIMPLE app to get expert feedback.

    How can I start intermittent fasting to see if it helps me?

    If you’re new to fasting, try starting with a 12-hour fast to get used to the practice.

    Remember that you can do intermittent fasting occasionally, so consider trying a fast every few days or once a week to start. Notice how you feel and ease into longer fasts gradually.If you’re just dipping your toes into the world of intermittent fasting, dive deeper with our beginner’s guide to intermittent fasting. And remember, every journey is better with a little guidance. Take our SIMPLE quiz and become a member of our supportive fasting family. We’re all about celebrating your milestones together!

    1. Abeyasekera KN. Benefits of intermittent fasting: A systematic review of randomized clinical trials. 2020 [cited 2023 Sep 27]; Available from: https://scholar.dominican.edu/physician-assistant-studies-student-articles/12
    2. Welton S, Minty R, O’Driscoll T, Willms H, Poirier D, Madden S, et al. Intermittent fasting and weight loss: Systematic review. Can Fam Physician. 2020 Feb;66(2):117–25.
    3. Dakic T, Jevdjovic T, Vujovic P, Mladenovic A. The less we Eeat, the longer we live: Can caloric restriction help us become centenarians? Int J Mol Sci. 2022 Jun 11;23(12).
    4. Song DK, Kim YW. Beneficial effects of intermittent fasting: A narrative review. J Yeungnam Med Sci. 2023 Jan;40(1):4–11.
    5. de Cabo R, Mattson MP. Effects of intermittent fasting on health, aging, and disease. N Engl J Med. 2019 Dec 26;381(26):2541–51.
    6. Popa AD, Niță O, Gherasim A, Enache AI, Caba L, Mihalache L, et al. A scoping review of the relationship between intermittent fasting and the human gut microbiota: Current knowledge and future directions. Nutrients. 2023 Apr 26;15(9).
    7. Altayyar M, Nasser JA, Thomopoulos D, Bruneau M Jr. The implication of physiological ketosis on the cognitive brain: A narrative review. Nutrients. 2022 Jan 25;14(3).
    8. Jensen NJ, Wodschow HZ, Nilsson M, Rungby J. Effects of ketone bodies on brain metabolism and function in neurodegenerative diseases. Int J Mol Sci. 2020 Nov 20;21(22).
    9. Kovács Z, Brunner B, Ari C. Beneficial effects of exogenous ketogenic supplements on aging processes and age-related neurodegenerative diseases. Nutrients. 2021 Jun 26;13(7).
    10. Mehrabani S, Bagherniya M, Askari G, Read MI, Sahebkar A. The effect of fasting or calorie restriction on mitophagy induction: A literature review. J Cachexia Sarcopenia Muscle. 2020 Dec;11(6):1447–58.
    11. Koppel SJ, Swerdlow RH. Neuroketotherapeutics: A modern review of a century-old therapy. Neurochem Int. 2018 Jul;117:114–25.
    12. Curtis WM, Seeds WA, Mattson MP, Bradshaw PC. NADPH and mitochondrial quality control as targets for a circadian-based fasting and exercise therapy for the treatment of Parkinson’s disease. Cells. 2022 Aug 4;11(15).
    13. Ooi TC, Meramat A, Rajab NF, Shahar S, Ismail IS, Azam AA, et al. Intermittent fasting enhanced the cognitive function in older adults with mild cognitive impairment by inducing biochemical and metabolic changes: A 3-year progressive study. Nutrients. 2020 Aug 30;12(9).
    14. Currenti W, Godos J, Castellano S, Caruso G, Ferri R, Caraci F, et al. Association between time restricted feeding and cognitive status in older Italian adults. Nutrients. 2021 Jan 9;13(1).
    15. Elias A, Padinjakara N, Lautenschlager NT. Effects of intermittent fasting on cognitive health and Alzheimer’s disease. Nutr Rev. 2023 Aug 10;81(9):1225–33.
    16. Gudden J, Arias Vasquez A, Bloemendaal M. The effects of intermittent fasting on brain and cognitive function. Nutrients. 2021 Sep 10;13(9).
    17. Phillips MCL. Fasting as a therapy in neurological disease. Nutrients. 2019 Oct 17;11(10).
    18. Leclerc E, Trevizol AP, Grigolon RB, Subramaniapillai M, McIntyre RS, Brietzke E, et al. The effect of caloric restriction on working memory in healthy non-obese adults. CNS Spectr. 2020 Feb;25(1):2–8.
    19. Liu Z, Dai X, Zhang H, Shi R, Hui Y, Jin X, et al. Gut microbiota mediates intermittent-fasting alleviation of diabetes-induced cognitive impairment. Nat Commun. 2020 Feb 18;11(1):855.
    20. Vasim I, Majeed CN, DeBoer MD. Intermittent fasting and metabolic health. Nutrients. 2022 Jan 31;14(3).
    21. Tinsley GM, La Bounty PM. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutr Rev. 2015 Oct;73(10):661–74.
    22. Clifton KK, Ma CX, Fontana L, Peterson LL. Intermittent fasting in the prevention and treatment of cancer. CA Cancer J Clin. 2021 Nov;71(6):527–46.
    23. Zang BY, He LX, Xue L. Intermittent fasting: Potential bridge of obesity and diabetes to health? Nutrients. 2022 Feb 25;14(5).
    24. Mattson MP, Longo VD, Harvie M. Impact of intermittent fasting on health and disease processes. Ageing Res Rev. 2017 Oct;39:46–58.
    25. Pérez-Gerdel T, Camargo M, Alvarado M, Ramírez JD. Impact of intermittent fasting on the gut microbiota: A systematic review. Adv Biol (Weinh). 2023 Aug;7(8):e2200337.
    26. Valicente VM, Peng CH, Pacheco KN, Lin L, Kielb EI, Dawoodani E, et al. Ultraprocessed foods and obesity risk: A critical review of reported mechanisms. Adv Nutr. 2023 Jul 1;14(4):718–38.
    27. Daas MC, de Roos NM. Intermittent fasting contributes to aligned circadian rhythms through interactions with the gut microbiome. Benef Microbes. 2021 Apr 12;12(2):147–61.
    28. Frank J, Gupta A, Osadchiy V, Mayer EA. Brain-gut-microbiome interactions and intermittent fasting in obesity. Nutrients. 2021 Feb 10;13(2).
    29. Hu X, Xia K, Dai M, Han X, Yuan P, Liu J, et al. Intermittent fasting modulates the intestinal microbiota and improves obesity and host energy metabolism. NPJ Biofilms Microbiomes. 2023 Apr 7;9(1):19.
    30. Patterson RE, Laughlin GA, LaCroix AZ, Hartman SJ, Natarajan L, Senger CM, et al. Intermittent fasting and human metabolic health. J Acad Nutr Diet. 2015 Aug;115(8):1203–12.
    31. Yamaguchi M, Uemura H, Katsuura-Kamano S, Nakamoto M, Hiyoshi M, Takami H, et al. Relationship of dietary factors and habits with sleep-wake regularity. Asia Pac J Clin Nutr. 2013;22(3):457–65.
    32. Antelmi E, Vinai P, Pizza F, Marcatelli M, Speciale M, Provini F. Nocturnal eating is part of the clinical spectrum of restless legs syndrome and an underestimated risk factor for increased body mass index. Sleep Med. 2014 Feb;15(2):168–72.
    33. Zhou Y, Jin Y, Zhu Y, Fang W, Dai X, Lim C, et al. Sleep problems associate with multimorbidity: A systematic review and meta-analysis. Public Health Rev. 2023 Jun 13;44:1605469.
    34. Paoli A, Tinsley G, Bianco A, Moro T. The influence of meal frequency and timing on health in humans: The role of fasting. Nutrients. 2019 Mar 28;11(4).
    35. Golbidi S, Daiber A, Korac B, Li H, Essop MF, Laher I. Health benefits of fasting and caloric restriction. Curr Diab Rep. 2017 Oct 23;17(12):123.
    36. Buettner D, Skemp S. Blue zones: Lessons from the world’s longest lived. Am J Lifestyle Med. 2016 Jul 7;10(5):318–21.
    37. Brandhorst S, Longo VD. Protein quantity and source, fasting-mimicking diets, and longevity. Adv Nutr. 2019 Nov 1;10(Suppl_4):S340–50.
    38. Brandhorst S, Longo VD. Fasting and caloric restriction in cancer prevention and treatment. Recent Results Cancer Res. 2016;207:241–66.