Is Fasting Healthy?

Mohit Sapru Posted On :
12 min, 2224 words

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For as long as Obesity has got humans concerned, it has been the endeavor of everyone affected to get rid of the extra kilos.

People put on weight by consuming more energy(measured as Calories) than they burn, so consuming lesser calories or energy would help reduce. Few other factors that result in overweight are genetic factors, metabolism, hormones, kind of food we intake, bloodtype and lifestyle.

As many as there are ways to put on weight, there are many to loose it too. Fasting or reducing food intake is one of the most common & widely adopted way to loose weight. But is fasting healthy?? and does it have any health benefits? Listen to the science behind what happens when the body is deprived of calories/energy. This audio is from the BBC's Crowd Science program aired on May25,2018 produced by Marijke Peters and presented by Marnie Chesterton.

Watch this interesting presentation "Fasting for Survival" from Dr. Pradip Jamnadas(a cardiovascular specialist based in Florida, USA) wherein he explains the biochemistry behind why fasting could save us and eating the 3-5 meals that humans normally do is probably the reason behind our ill health.

Few points worth noting from this lecture on the biochemistry behind fasting. . .

  • Eating is an energy intensive activity. For each intake of 100cal almost 60-70cal is spent in its digestion.
  • A normal human being has almost 50,000cal worth of energy normally stored as fat in their bodies which will begin to get utilzed when there is a deficit in the energy required for the body's processes.
  • After you stop eating, within the first 12hours, most of the glycogen [a polysaccharide of glucose which is how glucose is mainly stored in the body) in your liver and muscles will get used up and this is a normal thing. Thus the blood sugar/glucose level will get balanced/maintained, but not drop. Glucose is the main source of energy in the body and is produced by breaking down the cardohydrates in our meals and absorbed through the lining of the small intestine into the bloodstream. For the purpose of comparison even a 7day fast will result only in a drop in blood sugar(glucose) levels but never to the extent of making one hypoglycemic (Hypoglycemia is a condition in which your blood sugar (glucose) level is lower than normal) unless one is on insulin or taking diabetic medication.
  • After 12hours of stopping to eat a process called gluconeogenesis (GNG) starts to happen. The body begins to syntesize new glucose mainly in the liver using the amino acids from the protien in the muscles. This keeps the blood sugar(glucose) levels maintained for another 12hours.
  • In the 12hours after GNG there is a small increase in ketosis. Ketosis is a process where the body uses stored fat, instead of glucose, converting them into ketones which are then used as the main source of energy. But how does the body know when to begin using the stored fat?? The low insulin level because of no food intake triggers this process (When the insulin levels are high the body stores energy as fat and when low it pulls energy from fat). Once the fat stores are opened then through the action of hormone-sensitive lipase - whose main funtion is to mobilize the stored fats and Lipoprotein Lipase(LPL) - which acts like a gatekeeper for delivery of fat into the tissues in the body, the fat is converted into triglycerides and fatty acids. The fatty acids by way of blood stream endup in the liver where they are converted into ketones. Thus ketones are substances that get produced when the body has insufficient glucose(blood sugar).
  • Ketones produced is used by every cell in the body including the brain. The medical faternity has found that after a 7day fast about 70% of the energy required by the brain comes through ketones. Around 18hrs into fasting the ketone levels begins to rise and by 24hrs almost 10-15% of the energy needed is from ketones. As the fasting continues further into 36hrs or 5days the ketone levels are really high with not much of a problem to the body. Ketone levels are mesaurable using a urine dip stick to check if one has become ketogenic. NOTE higher ketone levels for people with type1 diabetes will lead to a risky condition called diabetic ketoacidosis (DKA). Also a person on a low carbohydrate or low sugar diet will become ketogenic earlier than someone who eats lots of sugar due to the fact that glycogen gets used up first before ketogenesis begins. As longs as ketogeneis is ongoing the fat stores of the body will keep on getting utilized and vice versa. Keep in mind that the only thing that prevents the fat stores from being used is the insulin in our bodies. Insulin, a hormone produced in our pancreas, comes into play only when we eat because it causes the cells in our bodies to act on the glucose for producing energy. So, as long as our insulin levels are high or as long as we keep eating, the body will derive the energy required from processing the glucose being made and not from the fat stores of the body through the process of ketosis. No wonder then the diabetics taking insulin find it impossible to loose weight.
  • Fasting makes the body sensetive to insulin, as insulin levels are low. When a meal is taken thereafter only a little amount of inulin is secreted to act on the little glucose produced. Thus the body deals with such a post fast meal and metabolises it in a much different manner as compared to if one ate again when body is already in a fed state. The benefits of fasting just for a day are far more rewarding due to increased insulin sensetivity leading to buring more fat. Caloric restrictive 5meals a day eating by comparion is not as benificial as done with fasting.
  • The other benefits apart from utilizing body fat and low insulin levels, after a fast are
    • increased metabolic rate(say around 18hrs into fasting) due to high adrenaline(also called epinephrine or fight-or-flight hormone) and cortisol levels. These are two hormones released by adrenal glands(which sit atop the kidneys) making you more alert.
    • Brain derived neurotropic factor (BDNF) protien is produced which help with the maintenance of existing neurons and promotes growth of new neurons(nerve cells) and synapses. BDNF is also responsible for long term memory.
    • increasing growth hormone levels. A medical study done concluded with 2000% increase in growth hormones after a 2day fast was done. Growth hormones are responsible for keeping you young and keeping your skin better and enable muscle growth.
    • promote Autophagy (starting at 18hrs and maximizes at 36hrs of fasting ) which is body's mechanism of clearing damaged cells in its organs and regenerating newer ones. Fasting is known to trigger Autophagy. And when you eat after you have had Autophagy a signal is sent to the bone marrow to borrow stem cells(cost you a fortune to have them externally) to replenish the loss of cells thus promoting a complete rejevunation.
    • reduce the chances of getting cancer by almost 70% as the cancerous cells die off first when you fast as they do not get their nutrients due to low glucose and inulin levels. Studies done on people receiving chemotherapy after a 3day fast have shown them to be able to tolerate the chemotherapy better, have less side effects and make their normal cells more resilient making the weaker cancerous cells die off earlier.
    • Increase in SIRT1(sirutin1 - one kind of protien from the sirutin family) enzymes levels and when that happens SIRT1 binds with acetyle groups on histones on the DNA (Histones are protiens responsible for giving a structure and compact shape to the DNA and preveting it from getting tangled and damaged). This in turn helps with gene expression or manufacturing of new protiens i.e gene regulation. Increased SIRT1 levels also activates the FOXO3 gene which is responsible for human longivity. The FOXO3 gene in turn (A).activates other genes like the antioxidant genes and the DNA repair mechanism (B).controls Apoptosis (If cells in are no longer needed, they commit suicide by activating an intracellular death program), and Autophagy (getting rid of old dead cells) as well as stem cell mobilization. Adequete levels of Vitamin-D in the body prevents deficiency of FOXO3 and so does intake of Omega-3, meditation, adequete sleep and eating the right kind of food(i.e no processed foods).
  • Benefits from fasting cannot be realised by just fasting overnight. Keep yourself properly hydrated during fasting. If the body is not hungry do not eat. You may get dizzy and have cramps when fasting but that is due to low blood pressure and not due to low sugar levels. Intake of salts(adding little salt to water) and magnesium(magnesium spary on skin) will help resolve these problems.
  • How does one decide which kind of fasting to go for...a day's fast OR a longer fast?? To just stay healthy, loose a bit of weight and general maintenance eat once a day or at the max 2 meals in a day with a gap of 6-8hours between both eatings. This is also known as time restricted feeding. Eating less frequently is the key here as each meal will only increase insulin levels and break ketogenesis. Then once a week eat only one meal a day and once every 6months go for a 7days fast. Too much of our lives focuses on eating.
  • Eat one fruit a day and not 5-6 different kinds. Too much fructose intake will only lead to weight increase. Eat fruits with low glycemic index(peaches, plums, pears, apricots, banana and not melons, grapes, kiwi fruit).
  • What you eat with every meal effects your genetic expression
  • Too much protien in diet produces more IGF1(Insulin Like Growth Factor1) which does help build muscles but also leads to cell poliferation that increases the risk of cancer. A protien rich diet unless required(medically or if you are growing or are involved in a heavy athletic activity) is not advisable. Amount of protien in our diet should not be more than 0.35gms per pound which we can normally get in our regular meals. Intake of protien powder is not a good idea.
  • Sugar(man made processed food and not available naturally) causes inflammation in the body.
  • Cancer, Heart disease, Diabaties, degenerative joint disease and infalmmatory bowels are conditions of old age. Staying young for longer by way of fasting, keeping weight in control, eating right food, healthy lifestyle, less stress will prolong the onset of these problems.
  • Going on a high carbohydrate diet and lowering the intake of natural fat makes you nutritionally deficient as the Vitmin A,D,E,K do not get absorbed (they only get absorbed with natural fat).
  • In the two and half million years of human evolution approximately 100,000 generations went past living a paleolithic existance and eating probably after hunting only once in a day(and sometimes once in 2-3days) with our diet consisting of mainly meat, some vegetables and lots of water. This continued till the agricultural period came upon us approx 12000years back which lasted for approx 600 generations leading to the present industrial age which has lasted in comparison for merely 10 generations. The dietary and lifestyle requirements of each of the 3 periods have had their influence on our genetic and physiological developement. How does changed eating habits of a mere 10generations mitigate the genetics of 100,000 generations?? Even as our dietary habits have changes post agricultural period till now our genetics are still that of our paleolithic existance. Our bodies are made to both fast as well as feast. Fasting is not a new wisdom.
  • To begin a fasting program first cut carbohydrate intake, no sugar, no processed or drink diet. Water, coffee and tea are OK. Make and use bone broth(dont buy readymade).
  • Individuals who are diabetic need to involve their physicians before starting a fasting program. For such a group the blood glusose level may rise during or after the fasting, but this is just temporary and not much of a problem area(as all it does is glycate the protiens). The real killer is high insulin levels.

Another video by Sadhguru on the concept of fasting

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