Updated: May 20
Intermittent fasting has been popularized over the last several years as first the Paleo movement gained steam, then the medical community started realizing the benefits. However, the idea of fasting is one that is steeped in ancient wisdom.
People of all types of religions have fasted as part of a spiritual ritual since as far back as our records show.
However, religion is not the only impetus to fast. In today’s blog I’ll break down for you the various reasons you might consider fasting, or intermittent fasting (IF). In a later article I will tell you more about how exactly you might implement fasting into your lifestyle, as well as considerations for when it might NOT be prudent.
This is the low hanging fruit on fasting. Pretty simple, really. Usually if you don’t eat, or eat quite a bit less, you will lose weight. By fasting for a few hours daily, or even whole days, clearly you are going to decrease your total caloric load and therefore lose some pounds. Though there may be one downside to long-term caloric restriction when it comes to keeping your metabolism in tip-top shape. It seems that the body down-regulates thyroid function. Specifically, it tends to lower T3. That’s not to say this would be a deleterious thing, but maybe just your body’s natural way of slowing things down when large amounts of food aren’t coming in regularly.(2)
DISEASE MANAGEMENT OR PREVENTION
One very intriguing benefit to fasting is that some diseases may be prevented or even treated with caloric restriction. Cardiovascular disease (CVD), diabetes, and cancer are the primary areas where research has been directed.(3,4) In the case of diabetes (type II), it’s simple to understand how fasting can help. Not only is weight loss happening which will help the body normalize leptin and blood sugar, but with a decrease in overall sugar intake, insulin sensitivity can be attained. Keep in mind, this only works on the assumption that the person fasting is not consuming high-sugar/starch foods when off their fast. In addition, any diabetic should be under direct medical supervision when attempting any new diet protocol as extremes in blood-sugar must be monitored.(5)
When we discuss CVD, the mechanism by which fasting works, is more related to inflammation. LDL cholesterol often improves, blood pressure lowers, BMI decreases, and detoxification pathways are enhanced.(6,7) Basically, when you give your body a chance to catch up and clean house, overall inflammation will clearly decrease.
To me, the idea of using intermittent fasting to manage cancer risk is very interesting. One theory on the way this works is that by starving the cancer cells of sugar, they can no longer thrive and grow.(8) However, some evidence suggests that this may not be the case because the body can create glucose from most any fuel and therefore there really is no way to “starve” a cancer cell. Another avenue of protection however, may be through a process called autophagy.
Autophagy refers to the process by which cells are allowed to clean house and basically get rid of all metabolic garbage.(10)
Autophagy, however, can be both helpful and harmful to cancer cells. While ridding the cells of their unhealthy organelles and metabolic by-products can keep cells healthy long-term, autophagy can work in the opposite way to aid cancer cells. When tumor cells undergo autophagy, they can actually become stronger and proliferate.(11) So the science is a still out on how fasting can help in regards to cancer treatment and prevention.
Autophagy also comes into play with how fasting affects longevity. Basically, the ability of cells to detoxify themselves directly relates to how well they survive. Healthy cells mean delayed aging.(12) Caloric restriction (CR) helps the body regulate energy expenditure and adjust metabolic activity as age and environment change.(13) This makes sense in an evolutionary perspective. If you were able to slow down your metabolic processes in order to survive times of famine, your ability to outlive your contemporaries was greatly increased.
Those who adhere to CR lifestyles tend to keep their total calories down by 20-40% compared to what they would normally need to eat. I should mention that it’s crucial that what few calories are consumed contain all the necessary building blocks (amino acids, fats, vitamins, minerals, etc) that one needs to thrive.(14) Utilizing IF to achieve caloric restriction might be an easier avenue as cutting all meals and snacks down by 20-40% might seem, well, just cruel. But skipping a meal every once in a while is a little easier on the mindset
What if skipping a meal here and there could make you smarter? Well, that’s what they were looking to find out in this study.(15) It appears that there may be some viability to the idea that fasting can indeed enhance brain function and even structure. To keep beating the autophagy horse, fasting increases neuronal autophagy, and therefore decreases aging of the brain. In addition, fasting increases brain-derived neurotrophic factor (BDNF). BDNF is crucial to neurons’ survival, aids in the creation of new neurons, and helps create synapses.(15) Furthermore, low levels of BDNF are strongly associated with the incidence of Alzheimer’s Disease.(16)
Fasting is also key in increasing ketone bodies. Ketones are produced when the liver runs out of glycogen and starts breaking down fatty acids (from body fat or ingested fat) for energy. These come in the form of beta-hydroxybutyrate (BHB), acetoacetone, or acetone.(17) These ketone bodies are then released into the bloodstream for use as energy. You should know that the brain accounts for about 20% of energy needs. BHB is even more efficient at fueling cells than glucose. In addition, high levels of ketones seem increase mitochondrial density in neurons, specifically in the hippocampus (responsible for emotions, memory, and spatial navigation).(18,19)
Okay, so I hope that all of this help you understand all the myriad of reasons why you might consider intermittent fasting. I have played with it myself over the last few years, and will be happy to go into further detail in the next blog.
Until then, tell me what you think. Do you fast? If so, when and why?
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