In some cases we can learn about the root cause of chronic disease by looking at how our environment and lifestyle has changed in the last few hundred years. On an evolutionary time scale of billions of years, a few hundred years is a very short time, and is not long enough for the body design to catch up with environmental changes.
For example in our previous two posts we noted how the body evolved (or was designed ) for continuously challenging movements in the quest for finding food , finding mates, seeking safety from predators and fighting off competitors, and how our current sedentary lifestyle is at odds with our body.
Another anomaly driven by evolutionarily recent changes in food production is the over-abundance of food. Our ancestors were more likely to face food scarcity, and a feast-or-famine type of existence. When food was scarce, our ancestors bodies smoothly switched from using glucose as fuel to using stored fat for energy. This means that they were more likely to mobilize reserves of body fat resulting in a higher fat-free mass.
Now the over-abundance of food combined with sedentary lifestyles has created an epidemic of obesity in which the global population of overweight and obese people exceeds that of under-weight people. Obesity is a risk factor for cardiovascular disease, diabetes, some cancers and emerging evidence suggests that it is also a risk factor for age related cognitive decline and possibly Alzheimer’s. According to researchers like Mark Mattson (Chief of the Laboratory of Neurosciences at the National Institute on Aging) and Bert Herring (Physician and Medical Writer), the root cause of the problem is not the excess storage of fat but rather, that the body needs fasting just like the muscles need exercise.
The idea of using fasting to improve health has existed for thousands of years as evidenced by the following quotes:
- “Humans live on one-quarter of what they eat; on the other three-quarters lives their doctor.” – Egyptian pyramid inscription, 3800 B.C.
- “Fasting is the greatest remedy– the physician within.” Philippus Paracelsus, one of the three fathers of Western medicine
- “A little starvation can really do more for the average sick man than can the best medicines and the best doctors.” Mark Twain, in My Debut As a Literary Person.
- “The best of all medicines is resting and fasting.” Benjamin Franklin
There is evidence that fasting has positive effects on the whole body such as decreased inflammation, oxidative stress and asthma, increased insulin sensitivity and decreased risk of diabetes, lower heart rate and blood pressure, and increase in human growth hormone.
There is also evidence that fasting helps to improve cognitive function by stimulating the production of neurotrophic factors and can help prevent chronic diseases such as Alzheimer’s and Parkinson’s.
According to Mark Mattson, the key to understanding how this works is to appreciate that our bodies have another mode of operation where energy is derived from fat metabolism (ketosis) rather than from glucose metabolism (glycolysis). When we eat three meals a day our bodies never switch over to this powerful mode of operation, because it takes 10 to 12 hours of fasting before the bodies glycogen stores are used up.
Fat is the Wealth of the Body
Every-day-life analogies for these two modes of operation would be like work vs vacation or like being employed vs unemployed. When you are in work mode you save cash for vacations or unexpected loss of income. As you can see from this example, each mode of operation entails a different set of priorities and tasks.
Likewise, fat is the stored wealth of the body and the bodies priorities shift depending on whether it is storing wealth (glycolysis) or using it (ketosis). Think of a short fast as a vacation mode for your body, while a longer fast may be more challenging (i.e. unemployment).
Mark Mattson promotes the idea that fasting is a challenge to the brain. This challenge promotes adaptive stress responses and changes in the brain similar to what is seen with vigorous exercise or cognitively challenging stimuli. This makes sense from an evolutionary perspective.
Using our analogy, an unemployed person is challenged to learn new skills in order to compete for a new job. Similarly the fasting brain responds to the challenge of acquiring more body wealth (fat), by generating neurotrophic factors that promote the development of new connections and that drive the transformation of stem cells into new brain cells in some regions of the brain.
The neurotrophic factor BDNF that is released during fasting also promotes the increase in the number of mitochondria inside cells. Because mitochondria are the powerhouses of cells this increases the ability of neurons to grow and develop new connections.
How to Feed Your Brain Fast
Knowledge is power when properly applied, so what is the right way to incorporate fasting into your life. Just like engaging in new physical activity it makes sense to discuss changes in lifestyle with your health care team. Care must be taken if you have high calorie expenditure due to athletic endeavors, or if you are taking medications.
Fasting can generally be started by increasing the amount of time between your last meal of the day and your first meal of the subsequent day. One could limit meals to an 8 hour window or less each day. This is the approach that I have been using, although my window is currently more like 10 hours.
Another option is to skip the last meal of the day or the first meal of the day once or twice each week. Just as an athlete must begin with light weights and progress to more difficult challenges in order to avoid injuries, so it is with fasting. Learn more about it and proceed with caution in order to make sure the body is receiving its needed supply of nutrients. It could be your ticket to a healthier you.