Fasting is an age-long practice among religious groups. Religious people fast for various reasons which are outside the scope of this blog.
Fasting which can be defined as voluntary and partial or total abstinence from food and drink for a period of time is also of great interest to nutritionist and health professional for its acclaimed health benefits.
The claim that fasting promotes good health (I should like to add that when it is done properly) has triggered many research works by scientists whose objectives are to validate or otherwise disprove these claims.
Personally, I have undertaken various kind of fasting ranging from partial to total abstinence (for religious reasons, primarily) and I can share first hand experience of both its health benefits and risks.
Sometimes, when I fast, I take only water especially when I go without eating for three or more days. At other times, I undertake what some in my religious circle refer to as dry fasting. In this type of fasting, one goes without eating or drinking anything for at least a day.
Health Benefits of Fasting
Prolonged fasting, according to a team of researchers from the University of Southern California in Los Angeles, clears the immune system of worn out cell and bring about the regeneration of new ones. They opined that fasting could protect against cell damages resulting from aging or chemotherapy and enhance longevity.
Intermittent fasting has also been shown to have many health benefits, although most of the research conducted on fasting has been on animals, not humans, yet the results are enlightening as well as promising.
Given that during the period of fasting, the body has no way of getting energy from food, it make use of glucose stored in the muscles and liver. This takes place about 8 hours from the last meal a person consumed.
Once, the body exhaust its stored glucose, its make use of energy stored in fat thus bringing about weight loss. Apart from enhancing weight loss, fasting helps preserve the muscles by using fat as energy and lower cholesterol level in the process.
According to Mark Mattson, a senior investigator for ageing in the National institute of Aging (which is part of the US National institute of health), fasting like vigorous exercise "stress" the cells of the body and the cells respond to the stress adaptively leading to their ability to cope with the stress and to perhaps resist diseases. This is one of many theories that researchers have put forward
to explain the physiological benefits of fasting.
In an experiment designed by Mattson and his colleague where overweight adults suffering from moderate asthma consumed 20 % of their normal calories intake on alternate days over a period of eight weeks, participants who adhered to the diet lost 8 % of their initial body weight. In addition, there was a decrease in the markers of oxidative stress and inflammation as well as improvement in the asthma-related symptoms and other quality-of -life indicators (You can find the scientific article here)
The usage of fat as energy source during fasting causes the release of fatty acids referred to as ketones into the bloodstream which protect the memory and learning functionality and slow disease processes in the brain according to Mattson.
Based on experimental results from numerous studies, fasting has been shown to reduce harmful protein production that provokes inflammation in the brain and to boost the production of a protein called brain-derived neurotrophic factor (BDNF).
In addition, fasting helps reduce the risk of developing type 2 diabetes, lowers blood pressure, improves insulin sensitivity, promotes the secretion of human growth hormone, improves body composition, prevents acne and clear the skin. It also offers protection from certain cancers.
If you have ever fasted for a reasonable length of time, no doubt, you are familiar with the strong urge to binge as if to recover the lost calories during the period of fasting once and for all!
If one yield to this urge to binge after a period of fasting, then whatever health benefit, particularly weight loss, that may have been accrued from fasting will be lost.
In an experiment conducted on mice, Dr. Stephen Freeland and his colleagues came to the same conclusion (You can find the original article here). In his own words:
Caloric restriction, undernutrition without malnutrition, is the only experimental approach consistently shown to prolong survival in animal models
He concluded his aforementioned study thus:
Intermittent fasting with compensatory overeating “did not improve mouse survival nor did it delay prostrate tumor growth
Health Risks of Fasting
Having mentioned a number of health benefits of fasting, it is time to consider the downside of fasting especially when it is practiced indiscreetly.
Fasting causes dehydration due to the fact that the body cannot obtain fluid from food. It is thus advisable that people who are fasting for a prolonged period of time take enough water.
Lack of food during fasting, result in the reduction of stomach acid which is responsible for food digestion and bacteria destruction, but smelling or thinking about food during fasting can trigger the brain to produce stomach acid resulting in heartburn.
From experience, it is usually very difficult not to think about food during the initial stage of fasting, in fact, it seems that I become unusually conscious of food during this period but if my fasting is prolonged enough, I seem to reach a threshold in which I am not bothered by the need to eat nor by other normal bodily cravings.
To be clear, I am not here recommending prolonged fasting but merely stating my experience with the practice. Everybody is different and it must be remembered that I stated earlier that my primary reason for fasting is not for its health benefit.
If fasting is done too often for a prolonged period, it can lead to malnutrition which is unhealthy. Also, it is advisable that pregnant women, people who are underweight or recovering from surgery as well as patient of diabetes abstain from fasting. In fact, if you have health challenges, consult with your doctor before embarking on any kind of fasting.
Obtaining the Health Benefits of Fasting without Fasting
Some researchers claimed that the health benefits of fasting can actually be obtained without fasting. This is done through a special kind of diet known as fasting mimicking diet (FMD) which is low in protein, low in unhealthy fat but high in healthy fats.
As the name implies, FMD mimic the effect of prolonged fasting by
stimulating the markers linked to fasting such as low glucose level and high level of ketone bodies.
In Conclusion
Fasting has a number of health benefits, if done discreetly. I will appreciate it greatly, if my readers share their fasting experiences with me in the comment section.
References
Intermittent fasting: the science of going without
Fasting: Health benefits and risks