Is dry fasting good for your body ?
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This post will unravel the Science of Fasting! The word ‘fasting’ or ‘to fast’ is a verb that means “to abstain from all food and drinks,” or in some situations “to eat only sparingly or of certain kinds of food”, especially as a religious observance. Religions and philosophies that practice fasting include: Buddhism, Christianity, Islam, Judaism, Taoism, Jainism, and Hinduism. Some cultures even fast for non-religious reasons.
Then there is Intermittent Fasting (IF) or periodic fasting, which has no religious connections, it is an eating pattern that cycles between periods of fasting and eating. There are several different ways to do intermittent fasting, you might try eating only during an eight-hour period each day and fast for the remainder-16:8 IF approach. Or you might choose 5:2 approach, which involves eating regularly five days a week. For the other two days, you limit yourself to one 500–600 calorie meal. There are many different IF schedules. Scientific studies show that IF turns on a ‘metabolic switch’ which can effectively help to manage some metabolic diseases and also in some cases reverse weight gain. But how do you do it? And is it safe? We will explore IF through the lens of science in the next article, stay tuned!
In this article, we will take a deep dive inside our mind and body to examine the chain of events which takes place when you abstain from eating food and drinking fluids for longer periods, such as 24, 36, 48 and 72 hour. This form of fasting is referred to as ‘dry fasting’.
Human body function in a tightly regulated manner; it loves routine, operates in circadian rhythm, follows an internal biological clock and maintains homeostatic balance between different biological processes. When you decide to abstain from food and water completely, this balance is disturbed, your body now operates in ‘stress’ mode. Dry fasting is generally done for religious reasons but some articles claim that they have potential health benefits like flushing of toxins, boosts immunity and digestion, lower blood sugar levels, improves cognitive function and mental clarity, reduces stress and prevents mental illnesses. Some wellness influencers and self-acclaimed heath experts go one step further, they claim that dry fasting will heal the kidneys.
Neither assertion is backed by scientific research, and the only concrete biological outcome of not drinking water is dehydration. Longer periods of dry fasting, are not necessarily better for you and may be dangerous. Going too long without eating might actually encourage your body to start storing more fat in response to starvation. Without drinking water (or any fluids) things can get pretty serious, it can lead to low blood pressure, stroke, kidney failure, coma or even death after 3-5 days of no fluids intake.
Humans and all animals need food and water to survive. Water is in every cell of our body. It constitutes 60% of your body weight, this percentage varies with age, sex, fat mass to lean muscle ratio and levels of hydration. Nearly all body’s functions depend on water, your blood is more than 90% water, where it helps to carry oxygen and nutrients, dissolve minerals and nutrients, regulate internal body temperature, flush out waste products, lubricate joints and even protect organs and tissues. Water isn’t only in blood, it is present in almost all major organs, your heart and brain are about 73% water, lungs are 83% water, muscles and kidneys are 79%, skin around 64% water and seemingly dry bones are also 30% water.
Maintaining a balanced water levels is essential to avoid dehydration. In a day, human adults lose about 2.5 to 3 litres of water. Under basal conditions (i.e., steady state with no exercise), we loose water through breath, perspiration, urine and bowel movements. However, water loss may increase in hot weather and with prolonged exercise.
If someone tries dry fasting for a full day, sensory receptors in the brain’s hypothalamus senses low water levels and immediately responds by signalling the release of anti-diuretic hormone (ADH). ADH causes the kidneys to create aquaporins, channels which help blood to absorb and retain more water leading to concentrated, dark urine. Under these conditions urine has a higher concentration of minerals and waste products. This is your body’s first response to conserve water. This will follow up with notable decrease in energy levels and mood swings. Due to no adequate supply of water, brain will struggle to perform at its full capacity which will lead to cognitive decline, headaches and irritable mood. Some people can also observe symptoms like dizziness or light headedness due to decrease in blood pressure. A dehydrated brain has to work harder to accomplish similar task when compared with a hydrated brain. In a dehydrated body, brain can temporarily shrink in size due to lack of water.
Besides brain, your kidneys take a toll too. Kidneys are the filtration units of our body, they filter out the toxins from blood and excrete out toxins, minerals and other waste products in the urine. Your body also excretes out toxins and unwanted stuff in the form of stools.
The kidneys need water to do their job of filtering out toxins from the blood and flushing them out from the body. If the kidneys don’t get enough water, you’re not going to eliminate in the same way. In fact, kidneys have to work harder to filter toxins and the excreted urine will be darker in colour and will contain higher levels of minerals and waste products.
Do you know? Colour of urine is a telltale sign of the level of hydration in your body. See the below chart for details:
Not much research has been done directly on dry fasting, but evidences from dehydration research suggest that people who do dry fasting for a day, risk side effects like developing kidney stones. Longer than that, and they start risking their life.
Dry fasting for just a day can make your skin dry and pale, and longer that that you can loose skin elasticity, fine lines and wrinkles will be more prominent, skin will turn grey in a matter of two days. Besides, restricting intake of any source of water can strain your eyes, you will feel pain in the eye sockets, find it hard to concentrate on objects. Muscles will feel fatigue and you will get tired soon. Dry fasting can mess up the digestive system, it can cause constipation and also decrease your metabolism. Furthermore, once you break the fast, i.e., you eat food or drink water, your body will absorb all the calories and convert it into fat.
Proponents say temporary fasts (caloric restriction) mildly stress cells, called eustress, somewhat similar to the stress from exercise and can help the body. There are scientific studies backing the benefits of water fasting (abstaining from only food), intermittent fasting, and caloric restriction fasting, however, there’s no evidence that not drinking water aids in this process. Additionally, not drinking water will not help to clear out toxins and do a deeper metabolic cleanup as popularised by few self-proclaimed heath experts, as under dehydrated state you’re not going to eliminate in the same way. There is no research substantiating the benefits of dry fasting but there are ample studies on the deleterious effects of dehydration on your body.
A person can survive weeks without food, meanwhile, the human body can only survive two to four days without water.
So friends, think wisely before doing dry fasting!
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Thanks Dr S, I learned something new today. Waiting for article on IF!