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Does intermittent fasting improve longevity?

Intermittent fasting is an increasingly popular approach to eating, and has touted benefits such as weight loss, improved mental clarity, and better sleep patterns. But does research support this eating approach for increasing lifespan? Here’s what the science says about intermittent fasting for longevity.

Sarah Achleithner, health and wellness writer
5 mins
Let’s face it - no one likes the idea of getting old. This, combined with the global trend of aging populations, has given rise to a new era of longevity research. Increasingly, people are looking for strategies to prolong their life span and extend their healthy years. 
Nutrition plays a key role in chronic disease prevention, and while there are many proposed dietary strategies for longevity, intermittent fasting has become an increasingly popular approach. But does intermittent fasting (IF) really help you live longer? Before diving into more details, let’s get a better understanding of intermittent fasting and how it works.

What is intermittent fasting?

The key characteristic of IF is cycling between periods of fasting and eating for specific times throughout the day or week. Unlike other popular diets that have strict food and nutrient requirements, time is the only real restriction with IF — which many people seem to like. Essentially, you can eat what you want on IF, providing that you consume food within your ‘eating window’. 
There are several approaches to IF that mostly vary by length of fast:
  • Time restricted feeding (TRF): Commonly referred to as the 16:8 Method, time-restricted feeding typically involves limiting your daily eating window to 8 hours followed by a 16-hour overnight fast. This method is one of the most standard approaches, and one that many people find easiest to start with. 
  • Alternate day fasting: With alternate day fasting, you fast every other day, typically eating freely on the non-fasting days, and consuming about 25% of your daily calorie needs on fasting days.
  • 5:2 diet: This strategy involves restricting energy intake to 500-600 calories two days a week and normal eating the other five days [1]. 
Though intermittent fasting does not dictate any specific dietary recommendations, limiting your intake to a specific eating window often reduces your caloric intake which can result in weight loss for some.
Learn more about the pros and cons of intermittent fasting for runners and cyclists.

What happens when you fast?

Intermittent fasting influences hormone levels, cell repair, metabolic rate, and gene expression. The effects of intermittent fasting are far-reaching, and many of them are directly tied to living a longer, healthier life. 
Fasting has been shown to enhance the secretion of growth hormone (GH), which can be beneficial for both fat loss and muscle gain [2]. IF activates autophagy (a process where new healthy cells regenerate), and it also produces profound metabolic changes (where it switches from burning glucose to fatty acids) [1]. 
Additionally, fasting has been proposed to be a method of increasing longevity via these physiological adaptations, as well as via increased protein and DNA stability, insulin sensitivity, and changes in the expression of genes related to aging and disease prevention [3]. All these processes are beneficial for human health and can promote longevity and healthy aging. 
Read more about what happens during different fasting intervals here.

Intermittent fasting and longevity

Potential benefits of IF include weight loss, improved heart health, blood sugar control, neuroprotection and protection against some forms of cancer, however, research on IF is still in its infancy for many indications.
  • Weight loss: Even without intentional calorie reduction, one study showed that 8-hour time-restricted-feeding produced weight loss in obese adults [4].
  • Cardiovascular health: Some studies have shown the benefits IF can have on several markers of heart health, including decreases in resting heart rate, circulating insulin, glucose, and homocysteine, total cholesterol, LDL cholesterol, and triglyceride levels, as well as reduced blood pressure [5,6]. 
  • Diabetes: Fasting can help control blood sugar levels and increase insulin sensitivity, both of which are key metrics in managing and preventing type 2 diabetes [5,6]. 
  • Neurological conditions: Though there has not been much research done in humans yet, animal models show promising evidence for the positive effect IF may have on cognitive ability, with potential neuroprotective and regenerative effects [1]. 
  • Cancer: Intermittent fasting shows great promise in both the prevention and treatment of certain cancers. Animal studies have shown that periodic fasting can be as effective as chemotherapy in several cancers and can even protect non-cancer cells from the effects of chemo [5]. 
  • All-cause mortality: Emerging evidence suggests that IF can reduce all-cause mortality. One study found that those who routinely fasted had a 45% lower mortality rate than those who did not fast regularly [8].

Who shouldn’t fast?

Although intermittent fasting can provide health benefits for many people, this method may not be for everyone. Fasting for long periods of time can cause headaches, lightheadedness, mood changes, constipation, fatigue, and irritability if not approached correctly. Additionally, IF can lead to inadequate nutrition intake (which can lead to deficiencies), reproductive problems, and reduced sports performance. This eating approach can be hard to manage in social situations, and it may mask disordered eating.
IF is not recommended for:
  • pregnant and lactating women;
  • young children;
  • the elderly;
  • those with compromised immune systems;
  • anyone with a history of disordered eating or eating disorders [7]. 
If you are uncertain whether intermittent fasting is a good idea for you, consult a Registered Dietitian or speak with your healthcare provider. 

Summary

Intermittent fasting is a unique approach to eating that does not dictate what you eat, but when you eat. There are several different approaches to IF, including TRF and alternate day fasting. Intermittent fasting appears to impact various physiological processes including hormone function, cellular regeneration, and metabolism, all of which have effects on your health. The potential benefits from IF include weight loss, improved cardiovascular health, and lower risk of developing chronic diseases, and thereby may increase longevity and overall wellbeing. Intermittent fasting is not for everyone, so it’s important to understand the risks and benefits before giving it a try. 
Disclaimer: The text, images, videos, and other media on this page are provided for informational purposes only and are not intended to treat, diagnose, or replace personalized medical care.
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Key Takeaways

  • The 16/8 method is the most popular approach to fasting, which involves limiting your daily eating window to 8 hours followed by a 16-hour overnight fast.
  • Intermittent fasting produces many beneficial biological changes in the body, which influences hormone levels, cell repair, metabolic rate, and gene expression.
  • The potential benefits from IF include weight loss, improved cardiovascular health, and reduced risk of developing chronic diseases, thereby increasing your longevity and overall wellbeing.
  • Although intermittent fasting offers a variety of health benefits, this method may not be for everyone, as it can cause headaches, lightheadedness, mood changes, fatigue, irritability, digestive issues, and even malnutrition if not approached correctly.

References

  1. Longo, V.D., Di Tano, M., Mattson, M.P. et al. Intermittent and periodic fasting, longevity and disease. Nat Aging 1, 47–59 (2021). https://doi.org/10.1038/s43587-020-00013-3
  2. Ho, K. Y., Veldhuis, J. D., Johnson, M. L., Furlanetto, R., Evans, W. S., Alberti, K. G., & Thorner, M. O. (1988). Fasting enhances growth hormone secretion and amplifies the complex rhythms of growth hormone secretion in man. The Journal of clinical investigation81(4), 968–975. https://doi.org/10.1172/JCI113450 
  3. Martin, B., Mattson, M. P., & Maudsley, S. (2006). Caloric restriction and intermittent fasting: two potential diets for successful brain aging. Ageing research reviews5(3), 332–353. https://doi.org/10.1016/j.arr.2006.04.002 
  4. Gabel, K., Hoddy, K. K., Haggerty, N., Song, J., Kroeger, C. M., Trepanowski, J. F., Panda, S., & Varady, K. A. (2018). Effects of 8-hour time restricted feeding on body weight and metabolic disease risk factors in obese adults: A pilot study. Nutrition and healthy aging4(4), 345–353. https://doi.org/10.3233/NHA-170036 
  5. Mattson, M. P., Longo, V. D., & Harvie, M. (2017). Impact of intermittent fasting on health and disease processes. Ageing research reviews39, 46–58. https://doi.org/10.1016/j.arr.2016.10.005 
  6. Crupi, A.N., Haase, J., Brandhorst, S. et al. Periodic and Intermittent Fasting in Diabetes and Cardiovascular Disease. Curr Diab Rep 20, 83 (2020). https://doi.org/10.1007/s11892-020-01362-4 
  7. Grajower, M. M., & Horne, B. D. (2019). Clinical Management of Intermittent Fasting in Patients with Diabetes Mellitus. Nutrients11(4), 873. https://doi.org/10.3390/nu11040873 
  8. Horne, B. D., Benjamin D Horne Search for more papers by this author, Bartholomew, C., Ciera Bartholomew Search for more papers by this author, Anderson, J. L., Jeffrey L Anderson Search for more papers by this author, May, H. T., Heidi T May Search for more papers by this author, Knowlton, K. U., Kirk U Knowlton Search for more papers by this author, Bair, T. L., Tami L Bair Search for more papers by this author, LE, V. T., Viet T LE Search for more papers by this author, Bailey, B. W., Bruce W Bailey Search for more papers by this author, Muhlestein, J. B., Joseph B Muhlestein Search for more papers by this author, & information, F. author disclosure. (2019, November 11). Abstract 11123: Intermittent Fasting lifestyle and human longevity in cardiac Catheterization Populations. Circulation. https://www.ahajournals.org/doi/10.1161/circ.140.suppl_1.11123