Health Benefits of Intermittent Fasting  

There are various mechanisms by which intermittent fasting (IF) regimens are hypothesized to produce health benefits. These include effects on (1) circadian biology, (2) the gut microbiome, and (3) modifiable lifestyle changes. When these variables are unfavorable, adverse metabolic consequences occur. 

Like other animals, humans have endogenous circadian clocks in their brains (hypothalamus) and organs (liver, muscle, fat). When these clocks are desynchronized, the risk of chronic disease increases. Feeding is a dominant cue for synchronizing peripheral clocks, and eating outside of normal hours, e.g., having late-night meals, may disrupt energy balance and contribute to an unhealthy metabolism. 

Metabolic dysregulation includes adverse changes in glucose-insulin and growth hormone balance. For example, night shift work disrupts circadian rhythm and is associated with increased risks of cardiometabolic disease and cancer. Fasting regimens excluding caloric intake after the early evening appear to improve energy metabolism.

Circadian rhythms influence gut function. For example, metabolic responses to glucose intake are slower at night than in the morning. Circadian rhythms influence the gut microbiome and, therefore, metabolic health. Time-restricted feeding helps maintain cyclical fluctuations in and diversity of the gut microbiome. In addition, resting the gut for most of the day reduces gut permeability. 

Activation of the gut-brain pathway during fasting helps to maintain energy balance by enhancing the integrity of the gut lining. Late-night eating disrupts these processes.

Fasting regimens have the potential to facilitate positive health behaviors. Obese adults doing IF consumed fewer calories, lost weight, and had better sleep and energy levels. On the other hand, numerous studies have reported that nighttime eating decreases sleep duration and quality, which can lead to insulin resistance. This is associated with an increase in the risks of obesity, diabetes, cardiovascular disease, and cancer. For those who can maintain eating during an 8-10 hour period and fasting for 16-14 hours every day can improve their circadian rhythms and gut microbiome health and, therefore, their overall metabolic health.

Note: Although I am a physician, the content in this article is not meant to diagnose, treat, cure or prevent illness or disease in the reader – it is for educational purposes only.

References

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