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Intermittent Fasting - Counting Hours Instead of Calories

The Bioregulatory Medicine Institute

plate of healthy food with a clock next to it.

If the notion of counting calories is something you strongly dislike, yet you have a desire to both shed weight and enhance your overall well-being, then you might find the concept of an intermittent diet appealing. This approach allows you to select the most suitable strategy that aligns with your lifestyle, and the focus shifts to counting hours rather than calories.

Types of Intermittent Fasting

Intermittent fasting has deep historical roots, practiced for millennia for religious reasons and offering a straightforward approach. However, numerous intermittent fasting methods exist, which focus on alternating periods of eating and fasting. Below, you'll discover a compilation of the most popular intermittent fasting approaches.

  1. Time-restricted eating (TRE): This approach involves consuming all meals and snacks within a designated time frame each day, typically spanning 6-12 hours, and abstaining from food during the remaining hours.

  2. 16/8 fasting: This method prescribes a 16-hour fasting period followed by an 8-hour eating window daily.

  3. Alternate-day fasting: This strategy alternates between regular eating days and fasting days, or days with substantially reduced caloric intake.

  4. 5:2 fasting: This technique encompasses regular eating for five days per week and severely restricting calorie intake to 500-600 calories on two non-consecutive days.

  5. Whole-day fasting: This method calls for a complete 24-hour fasting period once or twice weekly.

  6. The warrior diet: This approach involves consuming a single substantial meal at night while fasting during the daytime.

  7. The twice-a-week method: This technique involves standard eating for five days per week and fasting on two non-consecutive days.

  8. Periodic fasting: This tactic entails consecutive days or weeks of fasting, followed by a period of standard eating.

Current Research

As intermittent dieting garners increased attention, multiple studies are unearthing an array of benefits. A review from 2021 delved into the effects of intermittent fasting – specifically time-restricted eating, alternate-day fasting, and the 5:2 fasting approach – on markers of cardiometabolic health. This analysis demonstrated that all three fasting strategies led to moderate weight loss (ranging from 1% to 8% from baseline), with the most substantial losses observed in alternate-day fasting and the 5:2 fasting strategies. Across the board, participants consistently consumed fewer calories during the study (a range of 10% to 30% from baseline).

Moreover, these dieting techniques correlated with enhancements in blood pressure, insulin resistance, oxidative stress, and lipid levels. However, further research is imperative to ascertain whether these improvements benefited all participants or solely those with elevated baseline markers.

Microbiome Advantages

Intermittent fasting also exerts positive effects on gut health, fostering a more diverse gut microbiome, bolstering gut epithelial integrity, and diminishing pro-inflammatory bacteria. These outcomes significantly contribute to overall health. Below is a simplified outline of the core findings:

  • Intermittent fasting contributes to the reconstruction of the composition of gut microbes.

  • It leads to a major increase in the abundance of Akkermansia muciniphila and Lactobacillus - two beneficial gut bacterias.

  • It reduces the levels of pro-inflammatory taxa Desulfovibrio and Turicibacter bacteria – which are associated with inflammation.

  • It improves gut epithelial integrity, or the strength and function of the gut lining.

  • A strong gut lining is important because it acts as a barrier to prevent harmful substances from entering the bloodstream such as Lipopolysaccharides, which are toxins that lead to inflammation.

Prolonged Fasting and its Anti-Aging Effects

The periodic fasting strategy, especially prolonged fasting spanning four to five days, has been extensively explored by Dr. Joseph Antoun. As the co-Director of the Center for Health Policy at the University of Chicago and CEO of L-Nutra, Dr. Antoun has delved into its longevity advantages. The underpinning concept behind his approach is that the human body typically possesses ample fat reserves (fat and glycogen) to sustain it for two days. Subsequently, when the fasting period surpasses two days, the body signals its cells of a crisis, initiating a process called autophagy. Autophagy facilitates the body in recycling and eliminating degraded cellular components, thus fostering cellular renewal.

During extended fasting, every cell engages in autophagy, scouring its compartments to consume debris, rejuvenate, and cleanse. Autophagy, also termed self-eating or self-rejuvenation, can potentially mitigate biological age, rendering cells more youthful. It's important to note, however, that fasting exceeding five days may strain the body's resources.

For deeper insights into Dr. Antoun's work, consider tuning in to The Science of Self-Healing Podcast Episode #106 - Fasting Made Easy: The Nutrition Technology That Provides Prolonged Fasting Benefits – With Food!

Cardiovascular Gains

Intermittent fasting stands to enhance cardiovascular health by reducing weight, hypertension, dyslipidemia, and diabetes. It holds the potential to lower blood pressure, insulin resistance, oxidative stress, and levels of low-density lipoprotein cholesterol and triglycerides. Several hypotheses attempt to explain the mechanisms through which intermittent fasting yields improved cardiovascular outcomes:

  • Oxidative insult reduction: The Oxidative Stress Hypothesis posits that intermittent fasting mitigates oxidative stress, leading to fewer free radicals and reduced mitochondrial energy production, ultimately diminishing overall oxidative stress.

  • Circadian rhythm theory: This theory posits that our body's physiological processes are guided by evolutionary rhythms, optimally occurring at specific times. Disruption of these rhythms elevates the risk of chronic ailments. For instance, circadian misalignment stemming from late dinners heightens insulin resistance and diabetes risk. Nighttime eating can also disrupt sleep patterns, exacerbating insulin resistance, obesity, and cardiovascular issues.

  • Induction of a ketogenic state: Intermittent fasting can induce a ketogenic state, linked to decreased cardiovascular risk factors through heightened ketone production, known to lower blood pressure and adipose tissue.

Enhanced Mitochondrial Function

Last but not least, intermittent fasting can stimulate the formation of new mitochondria (the energy-generating organelles within cells), thus refining mitochondrial health and function. This contributes to increased vitality and diminished signs of aging.

Safety Considerations

Intermittent fasting is generally safe, seldom resulting in energy disturbances or heightened disordered eating tendencies. However, it might not be suitable for certain groups, including pregnant individuals, those with type 1 diabetes, children, those with immune deficiencies (including organ transplant recipients), or individuals susceptible to developing eating disorders. Fasting, among proven interventions like exercise, dietary adjustments, and sleep, can promote healthy aging. Why not experiment with one of the aforementioned strategies that aligns with your lifestyle?

It's crucial to understand that adapting to an intermittent fasting regimen doesn't grant free rein to indulge in any food. Practicing mindful consumption of a balanced, low-processed diet remains essential.

Although further research is warranted in the realm of intermittent dieting, existing studies suggest that for many of us, this is a strategy offering a myriad of health benefits we can confidently embrace.



  1. Dong TA, Sandesara PB, Dhindsa DS, Mehta A, Arneson LC, Dollar AL, Taub PR, Sperling LS. "Intermittent Fasting: A Heart Healthy Dietary Pattern?" American Journal of Medicine 133, no. 8 (2020): 901-907. doi: 10.1016/j.amjmed.2020.03.030.

  2. "Intermittent Fasting." Diets: A Guide to Health and Nutrition. Accessed August 17, 2023.

  3. Manoogian, Emily N. C., et al. "Time-restricted Eating for the Prevention and Management of Metabolic Diseases." Endocrine Reviews 43, no. 2 (2022): 405-436. doi: 10.1210/endrev/bnab027.

  4. Vasim, Izzah, Chaudry N. Majeed, and Mark D. DeBoer. "Intermittent Fasting and Metabolic Health." Nutrients 14, no. 3 (2022): 631. doi: 10.3390/nu14030631.

  5. Varady, Krista A., Sergio Cienfuegos, Miren Ezpeleta, and Kristin Gabel. "Cardiometabolic Benefits of Intermittent Fasting." Annual Review of Nutrition 41 (2021): 333-361. doi: 10.1146/annurev-nutr-052020-041327.

  6. Zhang, Li, Yuanshang Wang, Ying Sun, and Xin Zhang. "Intermittent Fasting and Physical Exercise for Preventing Metabolic Disorders through Interaction with Gut Microbiota: A Review." Nutrients 15, no. 10 (2023): 2277. doi: 10.3390/nu15102277.


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