The more I research this topic, the more excited I become about this new and powerful dietary strategy to maximize overall health and slow aging. This is a great example of how most of the new, complex scientific research findings on food and nutrition are simply telling us to look to our ancient past and adopt lifestyle habits that are consistent with our genome. Of course, fasting certainly isn’t new. Our genes were selected during the Late Stone Age when feast and famine were commonplace. We evolved this way. The abundance of food and frequent meals in our modern world is simply not compatible with our Stone Age genes.
So why fast? Isn’t lack of food a hardship that we (in the developed world) no longer need to worry about? Are we not very fortunate to have the luxury of 24/7 availability of food? On the contrary, since the 1930’s, scientists have known that calorie restriction will extend average and maximum lifespan in a variety of species, from yeasts to flies to dogs. Recently, calorie restriction was shown to significantly increase average lifespan in monkeys as well.
Calorie restriction, however, is very difficult to maintain over long periods. It is not easy to consistently undereat. Reducing calories by 20-40% can compromise muscle mass and strength, bone density, vitality and quality of life. What’s the point of living longer when you are frail and weak, and unable to enjoy all the pleasures of eating? Not for me! As discussed in this review, intermittent fasting provides the same life-extending benefits, including stress and disease resistance, as calorie restriction.
Intermittent fasting is much more practical, less demanding, and more consistent with our “feast & famine” genome. I believe the best and easiest approach is “time-restricted feeding.” This method involves fasting for about 16-18 hours and then “feasting” during a shortened window of about 6-8 hours. This can be done a few days per week, or every day. I myself typically skip breakfast and fast from dinner to lunch. Time-restricted feeding, in one sense, is not a true fast since you still eat – just in condensed period.
Among the other more popular fasting strategies are alternate day fasting and the 5:2 plan that involves eating 500 to 600 calories for two non-consecutive days and unrestricted eating the other five days. Consider drinking sugar-free green tea or sugar-free coffee during the fast to enhance its longevity effects. If you find fasting to be too difficult, believe it or not, you can add coconut oil and/or grass-fed butter to coffee or tea and still benefit from much of fasting’s health enhancing effects (avoiding carbohydrate and protein is the key). These healthful fats promote amazing satiety to power you through the fast (this modified fast will be explored in more detail in a forthcoming post).
The primary biological pathway by which fasting promotes robust health and longevity is through a “housekeeping” process called autophagy. Just as clutter, junk, and viruses must be monitored and removed from a computer to maintain its operating efficiency and extend its life, our cells use autophagy as a quality control mechanism to degrade and recycle damaged, defective, and “expired” cellular components in order to keep themselves functioning optimally. In times of nutrient emergencies (fasting), damaged materials are recycled to produce energy in the form of ATP for survival. At the same time, harmful, unwanted junk and debris is swept away. This cellular trash includes mutated cells and aggregates of protein such as the amyloid plaques found in the brains of Alzheimer’s patients. In fact, defective autophagy has been linked to cancer, neurodegenerative disease, and many other chronic disorders.
With regard to muscle health, intermittent fasting is a quality control mechanism that preserves muscle mass by degrading damaged proteins and promoting the differentiation of muscle stem cells into fresh, new muscle fibers.
Unfortunately, autophagy declines with increasing age. With progressive malfunctioning of this convenient surveillance and repair mechanism, mutated or damaged proteins accumulate and gum up the normal workings of the cell, leading to disease, aging, and death. A classic example of this phenomenon is the “wear and tear” pigment called lipofuscin. Lipofuscin accumulates in various tissues at a rate inversely correlated with longevity. It is considered a hallmark of aging.
A strong case is building that defective autophagy is a fundamental driver of the aging process. In fact, the best known methods to extend lifespan in animals are driven by increased autophagy. In various long-lived mutant species of laboratory animals and insects, inactivation of autophagy genes suppressed the life span extension brought about by various longevity pathways including dietary restriction. Autophagy appears to be the common denominator among longevity interventions!
The remarkable longevity effects of fasting – primarily by way of autophagy – are the end result of all the numerous other benefits (e.g., increased insulin sensitivity) of fasting (to be discussed in future posts). Fasting is also an example of hormesis – an adaptive response by the body’s cells to mild stress resulting in stronger and more age-resistant cells. Weight training, whereby muscle fibers are damaged but subsequently grow stronger, is another common example of hormesis.
To further promote autophagy, complement intermittent fasting with acute, high-intensity exercise to achieve optimal levels of AMPK – a critical enzyme that acts as a master switch to regulate energy metabolism. AMPK activation drives autophagy and improves cellular stress resistance, thus playing a major role in the aging process. While “good stressors” such as fasting and exercise boost AMPK, this effect declines with increasing age. Fortunately, two botanical extracts that have been safely used for centuries can very effectively restore youthful AMPK activity. These extracts, Gynostemma pentaphyllum and Trans-tiliroside, have profound effects on reducing belly fat, normalizing blood sugar, and lowering serum lipid levels (more on AMPK in next post). Quercetin, resveratrol, curcumin, and EGCG (from green tea) can also activate AMPK.
To fight the enemy of aging, stress your body intermittently with fasting and high-intensity exercise. To quote the German philosopher, Friedrich Nietzsche: “That which does not kill us, makes us stronger.”