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How to Use the World’s Drug-Free “Wonder Drug”

effects of fasting

By Kelley Herring

There is a lot of misinformation when it comes to “conventional” health and dietary advice. For example, conventional wisdom tells us that “Breakfast is the Most Important Meal of the Day”. But the truth is that this bit of advice did not come from a scientific study. Instead, the origin was a 1944 marketing campaign by General Foods for the purposes of selling more cereal!

Conventional wisdom also tells us to “eat three square meals” a day. And to eat snacks in between meals to keep energy levels up and prevent “slowing your metabolism”. We’ve even been told that skipping meals can be harmful to our health.

The evidence against this cycle of continuous consumption is all around us, as overwhelming rates of chronic disease and obesity are the norm.

The truth is that humans were never meant to eat three scheduled meals (with snacks in between). Our ancestors ate when food was available and when it was acquired through toil and effort. We adapted the ability to function at a high level during extended periods without food. This was fundamentally important in our evolutionary history – and it is hardwired into your physiology.

Today, you will discover:

Conquer Cravings, Create Vibrant Health & Master Your Metabolism the Ancestral Way

If you follow the health headlines, you already know that intermittent fasting (IF) has become one of the latest “biohacks” that promises to help you shed those stubborn pounds.

Instead of counting calories, measuring macros or focusing on specific foods, the focus of intermittent fasting is on when (and when not) to eat. By creating designated windows for “eating” and “fasting” metabolic processes are optimized, leading to weight loss.

And this modern way of eating is fully aligned with how our ancestors ate, simply out of necessity.

Sometimes food was plentiful and bellies were full. Other times, food was scarce and we had to rely on body fat and stored glycogen for fuel. And, of course, with no refrigeration most food was gathered or hunted and consumed on the same day – with nothing to eat until that important work was done.

But research shows that the benefits of IF go far beyond weight loss…

In fact, fasting is like a complete overhaul for your metabolic machinery, impacting all your organ systems, cells and biochemistry!

effects of fasting, OMAD, one meal, feast and fast

Renew & Regenerate Your Body with Fasting

Studies show that periodic fasting is one of the most effective ways to:

  1. Regulate blood sugari
  2. Reverse insulin resistanceii
  3. Restore sensitivity to leptin (a hormone which helps control hunger and energy metabolism)iii
  4. Prevent canceriv,v
  5. Protect the brainvi
  6. Protect the heartvii
  7. Reduce risk of Alzheimer’s and Parkinson’sviii
  8. Promote stem cell regenerationix
  9. Reduce inflammationx,xi
  10. Improve immunity and reverse autoimmunityxii,xiii
  11. Calm digestive distress and promote a healthy microbiomexiv
  12. Reduce bone lossxv

With a laundry list that encompasses our most pressing health concerns of today, it is fair to say that fasting is truly “The World’s Drug-Free Wonder Drug”!

But how long must you fast to attain these incredible health benefits?

fasting, stroke risk, heart failure, covid-19, superbugs, food shortages

The Food-Free Zone: How Long Should You Fast?

The most popular cadence for intermittent fasting is 16/8. That is 16 hours of fasting followed by an eight-hour window in which food can be consumed. Others follow 20/4 or 22/6 fasting and feeding windows. And all of these have been shown to offer benefits.

In fact, researchers at the University of Illinois conducted the first human clinical trial of its kind to compare the effects of 20/4 and 22/6 fasting on body weight, cardiovascular and metabolic risk factors.

Study participants were divided into two groups. The 20/4 group was instructed to eat between the hours of 1 pm and 5 pm. Participants in the 22/6 were asked to eat between the hours of 1 pm and 7 pm. In both groups, the participants were allowed to eat whatever they wanted – as long as it was confined to their specific eating window. During the fasting hours, participants drank water or calorie-free beverages only.

The researchers followed the participants for 10 weeks, tracking their weight, insulin resistance, oxidative stress, blood pressure, LDL, HDL, triglycerides and inflammatory markers.

They discovered that both groups reduced calorie intake by an average of 550 calories each day, compared to their pre-study averages. The subjects also lost 3% of their body weight on average. They also found that insulin resistance and oxidative stress markers were reduced in both groups. And there was no difference in weight loss or cardiometabolic factors between the two groups.xvi

Dr. Krista Varady, PhD, one of the lead authors on the study says that, “It’s telling that there was no added weight loss benefit for people who sustained a longer fast.”

So, longer fasts are not necessarily better. But what about the different effects of fasting between men and women?


Fasting Safely for Women: Key Considerations

Intermittent fasting can provide amazing benefits for men and women alike. However, some research shows that women are more sensitive to the negative effects of fasting.

For example, a study published in Obesity Research found that alternate-day fasting can actually worsen glucose tolerance in women… while it improves this measure in men.xvii

The reason: Hormones.

You see, the hormones that regulate the monthly cycle in females are heavily influenced by food and glucose.xviii Prolonged fasting can lead to menstrual irregularity (including a complete loss of menstruation) for some women, as well as reduced bone density.xix

Now, this does not mean that women cannot fast safely and enjoy the numerous health benefits! It just means women need to pay attention to how they feel while fasting and start slowly. Here are a few tips:

  • Start with shorter fasts (10-12 hours), a few days per week. Work up to 16 hours of fasting a few days a week. If that goes well, consider fasting more days per week.

  • Work with a health care practitioner to evaluate your fasting regimen. If you already have hormone or thyroid issues, it is important to keep an eye on those markers.

  • Do not fast if you are under 18, pregnant or breastfeeding

During your fast, take note of how you feel. How is your body is responding? Pay attention to your energy levels and sleep quality. Worsening PMS, late or long periods, mood swings, headaches and difficulty concentrating are signs that your body is under too much stress, and fasting should be reduced.xx,xxi

It’s also important to discuss intermittent fasting with your health care practitioner if you have ever had an eating disorder, are underweight, suffer from Celiac disease or Crohn’s (which are linked to nutrient deficiencies), or if you have ever been diagnosed with diabetes, low blood sugar (hypoglycemia), thyroid or adrenal disease.

The Yin & Yang of Fasting & Feasting

Fasting is a powerful “nutritional” tool that can bring about real and rapid change in your body and your health.

It’s important to remember that intermittent fasting is NOT a diet. Ensure that you are eating enough during your “eating window” by filling your plate with nutrient-dense, whole foods, including grass-fed beef, organ meats, wild seafood, pastured pork and poultry, farm-fresh eggs, raw dairy and above ground veggies.

kelley herring


Kelley Herring is the author of the brand new book Keto Breads – which includes more information you need to know about why it is so important to avoid wheat and grains in your diet, plus how to use healthy replacements for these foods to create all the breads you love… without the gluten, carbs and health-harming effects. Click here to learn more about Keto Breads


i Varady KA, Hellerstein MK. Alternate-day fasting and chronic disease prevention: a review of human and animal trials. Am J Clin Nutr. 2007;86:7–13.

ii  Halberg N, Henriksen M, Soderhamn N, et al. Effect of intermittent fasting and refeeding on insulin action in healthy men. J Appl Physiol. 2005;99:2128–2136.

iii Sinha MK, Opentanova I, Ohannesian JP, et al. Evidence of free and bound leptin in human circulation. Studies in lean and obese subjects and during short-term fasting. J Clin Invest. 1996;98(6):1277–1282. doi:10.1172/JCI118913

iv Nencioni A, Caffa I, Cortellino S, Longo VD. Fasting and cancer: molecular mechanisms and clinical application. Nat Rev Cancer. 2018;18(11):707-719. doi:10.1038/s41568-018-0061-0

v Brandhorst S, Longo VD. Fasting and Caloric Restriction in Cancer Prevention and Treatment. Recent Results Cancer Res. 2016;207:241-266. doi:10.1007/978-3-319-42118-6_12

vi Anson, RM, Guo, Z, de Cabo, R, Iyun, T, Rios, M, Hagepanos, A, Ingram, DK, Lane, MA, Mattson, MP. Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake. PNAS May 13, 2003 100 (10) 6216-6220.

vii Varady KA, Bhutani S, Church EC, Klempel MC. Short-term modified alternate-day fasting: a novel dietary strategy for weight loss and cardioprotection in obese adults. Am J Clin Nutr. 2009;90(5):1138-1143. doi:10.3945/ajcn.2009.28380

viii Mattson MP. Energy intake and exercise as determinants of brain health and vulnerability to injury and disease. Cell Metab. 2012;16(6):706–722.

ix Mihaylova MM, Cheng CW, Cao AQ, et al. Fasting Activates Fatty Acid Oxidation to Enhance Intestinal Stem Cell Function during Homeostasis and Aging. Cell Stem Cell. 2018;22(5):769-778.e4. doi:10.1016/j.stem.2018.04.001

x Mattson, MP, Longo, VD, Harvie, M. Impact of intermittent fasting on health and disease processes. Ageing Res Rev. 2017 Oct;39:46-58. PMID: 27810402

xi Longo, VD, Mattson, MP. Fasting: molecular mechanisms and clinical applications. Cell Metab. 2014 Feb 4;19(2):181-92. PMID: 24440038

xii Choi IY, Piccio L, Childress P, et al. A Diet Mimicking Fasting Promotes Regeneration and Reduces Autoimmunity and Multiple Sclerosis Symptoms. Cell Rep. 2016;15(10):2136-2146. doi:10.1016/j.celrep.2016.05.009

xiii Cheng CW, Adams GB, Perin L, et al. Prolonged fasting reduces IGF-1/PKA to promote hematopoietic-stem-cell-based regeneration and reverse immunosuppression [published correction appears in Cell Stem Cell. 2016 Feb 4;18(2):291-2]. Cell Stem Cell. 2014;14(6):810-823. doi:10.1016/j.stem.2014.04.014

xiv Rangan P, Choi I, Wei M, et al. Fasting-Mimicking Diet Modulates Microbiota and Promotes Intestinal Regeneration to Reduce Inflammatory Bowel Disease Pathology. Cell Rep. 2019;26(10):2704-2719.e6. doi:10.1016/j.celrep.2019.02.019

xv Brandhorst S, Choi IY, Wei M, et al. A Periodic Diet that Mimics Fasting Promotes Multi-System Regeneration, Enhanced Cognitive Performance, and Healthspan. Cell Metab. 2015;22(1):86-99. doi:10.1016/j.cmet.2015.05.012

xvi Sofia Cienfuegos, Kelsey Gabel, Faiza Kalam, Mark Ezpeleta, Eric Wiseman, Vasiliki Pavlou, Shuhao Lin, Manoela Lima Oliveira, Krista A. Varady. Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity. Cell Metabolism, 2020; DOI: 10.1016/j.cmet.2020.06.018

xvii Heilbronn LK, Civitarese AE, Bogacka I, Smith SR, Hulver M, Ravussin E. Glucose tolerance and skeletal muscle gene expression in response to alternate day fasting. Obes Res. 2005;13(3):574-581. doi:10.1038/oby.2005.61

xviii Meczekalski B, Katulski K, Czyzyk A, Podfigurna-Stopa A, Maciejewska-Jeske M. Functional hypothalamic amenorrhea and its influence on women’s health. J Endocrinol Invest. 2014;37(11):1049-1056. doi:10.1007/s40618-014-0169-3

xix Meczekalski B, Katulski K, Czyzyk A, Podfigurna-Stopa A, Maciejewska-Jeske M. Functional hypothalamic amenorrhea and its influence on women’s health. J Endocrinol Invest. 2014;37(11):1049-1056. doi:10.1007/s40618-014-0169-3

xx Heilbronn LK, Smith SR, Martin CK, Anton SD, Ravussin E. Alternate-day fasting in nonobese subjects: effects on body weight, body composition, and energy metabolism. Am J Clin Nutr. 2005;81(1):69-73. doi:10.1093/ajcn/81.1.69

xxi Harris L, Hamilton S, Azevedo LB, et al. Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis. JBI Database System Rev Implement Rep. 2018;16(2):507-547. doi:10.11124/JBISRIR-2016-003248