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8 Benefits of Prolonged Fasting

Do prolonged fasting periodically and reap the many benefits of prolonged fasting including accelerated weight loss.
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Prolonged fasting can accelerate your weight loss efforts. Learn how to do a 72 hour or more prolonged fast safely and reap the many other prolonged fasting benefits for your health and well-being.

Written by
Jill Lebofsky
15+yr Women's Wellness Expert, Holistic Menopause Support, Intermittent Fasting, Midlife, Essential Oil, Author, Speaker

The idea of not eating for multiple days in a row may seem overwhelming. But when done safely, a prolonged fast can be the best way to reset your body and achieve your wellness goals.

Prolonged fasting refers to fasts of 3 days or longer. There has been significant intermittent fasting research on the 16/8, the 5:2, alternate day fasting, and the 24-48 hour fast, but the research on prolonged fasting is limited.

Prolonged fasting is simply next-level intermittent fasting. The fasting time is extended a notch, and the results are magnified. With intermittent fasting, you are eating 1-2 meals during the day with a period of fasting typically 14-18 hours; with prolonged fasting, you don't eat anything during the entire multi-day fast.

When you take a break from eating for 3, 5, 7 – even up to 21 days – your body enters “survival mode”. Your body's systems, including your digestive system, get a well-deserved rest, and your body starts other processes that provide benefits you might never otherwise receive without prolonged fasting (1).

Prolonged fasting benefits

Think of prolonged fasting as a periodic add-on to a healthy lifestyle, not as a means of extreme dieting. The benefits go well beyond weight loss. 

Alt text Prolonged fasting can improve memory.

  1. Improved Memory – As we age, our memory is no longer what it used to be. Prolonged fasting can help by stimulating brain cell regrowth and regeneration of the hippocampus, the part of the brain responsible for memory (1).

  1. Increased Stem Cell Reserves – Stem cells have “the potential to develop into many different types of cells in the body. They are a repair system for the body”(2). Stem cells are there for use when other cells become damaged. Reserves deplete with age, and stress accelerates their depletion. Prolonged fasting can help to maintain stem cells (3).

  1. High Energy Levels – You may falsely believe that all you'll want to do when prolonged fasting is nap, but the opposite is true. Your energy level will soar as you burn your stored fat instead of newly eaten calories for energy.      

  1. Decreased Inflammation – Chronic inflammation damages the whole body and is a frequent cause of pain and disease. Prolonged fasting can decrease inflammation markers (4).

  1. Anti-Aging – Fasting triggers the release of the Human Growth Hormone (HgH), responsible for boosting metabolism, burning fat, and making you look younger. HgH is sometimes referred to as "The Fountain of Youth." Although HgH production slows as you age, one study showed that HgH production increased by 500% after fasting for 2 days (5).

  1. Reduces oxidative stress – Our cells need oxygen to survive. But oxygen is also a very reactive molecule that causes oxidative stress. Toxins in the environment and smoking can further accelerate oxidative stress. Prolonged fasting puts the body into repair mode, which stimulates antioxidant defense mechanisms (6).

  1. Autophagy – During a prolonged fast, one gets to really take advantage of the body's natural cell recycling system. Fasting triggers autophagy to rid itself of the damaged cells that cause issues and replace them with new, cleaned cells. Autophagy has anti-aging effects, supports the immune system, and decreases inflammation (7).

  1. Weight Loss – If you aren't consuming any calories for multiple days, you will probably notice a difference on the scale. You will also notice body shape changes when your body starts burning fat for energy in the absence of food.
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The Downsides Of Prolonged Fasting

Prolonged fasting can have some downsides.

Extreme Hunger – Not eating for days may cause hunger pains, dizziness, and insomnia. But hunger usually resolves after 2-3 days. 

Risk of Dehydration and Electrolyte Imbalance - Much of our water intake comes via food, and when you aren't eating food, you need to make sure you drink enough water to avoid dehydration. Also, you need to replenish your electrolytes, the salts that help maintain proper body functioning, such as sodium and potassium (8). 

Foul Mood- Some people get "hangry" (hungry + angry) when they don't eat.

What Can You Consume During Prolonged Fasting?

Coffee during prolonged fasting.

If you want to adhere to a clean prolonged fast, you are only allowed water, unsweetened tea, black coffee, and sea salt. Bone broth is suggested if you are struggling to maintain the fast.

How To Do Prolonged Fasting

Here is some advice that you should keep in mind when doing a prolonged fast:

  • Consult a doctor before starting, especially when you're on medications
  • Build up fast length time slowly
  • Stay hydrated
  • Take a multi-vitamin mineral and sea salt.
  • Light exercise
  • Distract yourself to stop thinking about food
  • Restart eating slowly when the fasting period is over
  • Stop at any point if you are feeling unwell

You should not do prolonged fasting if pregnant, breastfeeding, have a history of eating disorders, or if you are already thin (BMI < 19) and can't afford to lose any more body weight.

Bottom line

Prolonged fasting can be another amazing tool for your healthy living toolbox. Fasting for three or more days, periodically, leads to accelerated weight loss, has anti-aging benefits and decreases inflammation. Build up to the prolonged fast slowly and stay hydrated for the duration of the fast. Make sure to break your fast slowly when returning to your regular eating schedule.

You might be interested in reading our other article "Should I fast daily ?".


  1. Baik S-H, Rajeev V, Fann DY-W, Jo D-G, Arumugam TV. Intermittent fasting increases adult hippocampal neurogenesis. Brain and behavior. 2020 Jan; 10(1): e01444. doi: 10.1002/brb3.1444.
  2. Stem Cells. MedlinePlus. 2021. 
  3. Cheng C-W, Adams GB, Perin L, et al. Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression. Cell stem cell. 2014 Jun 5; 14(6): 810–823. doi: 10.1016/j.stem.2014.04.014.
  4. Aksungar FB, Topkaya AE, Akyildiz M. Interleukin-6, C-reactive protein and biochemical parameters during prolonged intermittent fasting. Annals of Nutrition and Metabolism. 2007;51(1):88-95. doi:10.1159/000100954.
  5. Hartman ML;Veldhuis JD;Johnson ML;Lee MM;Alberti KG;Samojlik E;Thorner MO; Augmented growth hormone (GH) secretory burst frequency and amplitude mediate enhanced GH secretion during a two-day fast in normal men. The Journal of Clinical Endocrinology and Metabolism. 1992 Apr;74(4):757-65. doi: 10.1210/jcem.74.4.1548337.
  6. Vázquez-Medina JP, Crocker DE, Forman HJ, Ortiz RM. Prolonged fasting does not increase oxidative damage or inflammation in post weaned northern elephant seal pups. The Journal of Experimental Biology. 2010 Jul 15; 213(14): 2524–2530. doi: 10.1242/jeb.041335.
  7. Netea-Maier RT, Plantinga TS, van de Veerdonk FL, Smit JW, Netea MG. Modulation of inflammation by autophagy: Consequences for human disease. Autophagy. 2016 Feb; 12(2): 245–260. doi: 10.1080/15548627.2015.1071759.
  8. Weinsier RL. Fasting-A review with emphasis on the electrolytes. The American Journal of Medicine.  1971 Feb; 50(2): 233-240. doi: 10.1016/0002-9343(71)90152-5

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