How does the body get energy during fasting?

- Discovery: Dr. Vihari shadow

- In the early stages of fasting, amino acids are converted into glucose by the liver and as the fasting progresses, both the liver and the kidneys begin to do this work.

There are many reasons to fast. In the month of Shravan, in Navratri, or during certain fasts, Hindus fast. Jains fast during Paryushana. Some people fast for political reasons. Also some people fast for health reasons, some people also fast to lose weight. The nutrients that are stored in the body during that time provide frugal nutrition to the body during fasting. But some people fast to death or they have to. For example, in Jainism, there is a practice of fasting till death called 'Santharo'. Apart from this, when there is a big earthquake, people have to face starvation for days without water and food under the rubble and even in the case of a terrible drought, people have to face starvation. In all these cases, the body relies on its own stored nutrients to survive. Everyone has a limit when it comes to fasting. The body copes until the end but in the end it can also get lost.

So we need to know where do we get energy during fasting? Are energy sources stored in our body? If nutrients are accumulated, how does the body use them during fasting? And for how long? We need to know when the body gets tired of losing.

So usually our average diet consists of 3% carbohydrates, 5% protein and 10% fat. Most of the carbohydrates absorbed from our diet go to the liver. Where it is converted to glycogen. Glycogen is broken down into glucose. And converted to fatty acids. It eventually produces triglycerides. Triglycerides are a type of fat. How much of this glucose is stored as fat in the cells of adipose tissue (fat tissue) and how much energy is supplied to different parts of the body.

Protein mixed in food also enters the blood and lymph in the form of amino acids. We know that a chain of atoms of about twenty amino acids gives one atom of a protein. Now the above amino acids obtained from food protein go to the liver and other tissues of the body. After ammonia is removed from the liver, it is converted to keto acid. In addition, ammonia is converted to urea. It is excreted in the bloodstream through the kidneys through the bloodstream. Oxidation of keto acids in the liver produces carbon dioxide and water as well as energy.

The fat we take in food is absorbed as triglycerides in the lymph and stored in adipose tissue. Adipose tissue stores a large amount of fat in our body.

The main source of energy in our body is glucose. The most important consumer of glucose is our brain. Two-thirds of the body's blood glucose is used by the brain. This nourishment of the brain should continue. During fasting, all the organs of our body sacrifice everything to take care of the brain.

How long a man can live without food depends on his health or climate etc. A healthy man can easily go hungry for 15 days without any harmful effects. However, fasting greatly reduces a person's physical capacity. Fasting or starvation stops the absorption of nutrients in the diet and therefore lowers blood glucose levels. So the question is where does the body get its energy from?

In the absence of fresh nutrition during fasting, the body first breaks down the glycogen stored in the liver and produces glucose to maintain the level of glucose in the blood. Blood sugar levels are maintained by the two pancreatic hormones insulin and glucagon. In the absorption phase, amino acids are converted into proteins. Carbohydrates and fatty acids are converted to glycogen and triglycerides, respectively. The amount of endocrine glucagon is low over that period of time but when the blood sugar level drops the glucagon level goes up and glycogen is broken down and supplies glucose. So glucose i.e. the amount of sugar in the blood increases. Later proteins and last fats are broken down to provide the body with the energy it needs.

The liver is low in glycogen. It provides about 200 calories of energy. The body needs 1500 to 2000 calories of energy in a day. So storage of the lever is not enough for more than a few hours. Also, not all glycogen in the liver can be used. Some of it has to be stored for emergencies. The fasting person needs it when a situation of severe stress arises. So long-term fasting provides only the stored protein and fat that the body needs for energy.

The amino acids and proteins accumulated in the skeletal muscle (the muscles that bind the skeletal bones) form the second line of defense of nutrition. When the glycogen available in the liver is used, the glycogen in the skeletal muscle is broken down and converted into amino acids. All these amino acids are converted into glucose by the liver in the early stages of fasting.

Thus in the early stages of fasting amino acids are converted into glucose by the liver and as the fasting progresses this work begins to be done by both the liver and the kidneys. The kidneys work harder. Skeletal muscle forms another line of defense against protein and glycogen fasting, but protein cannot be used indefinitely. The rate at which it is initially consumed, if it continues to be consumed at that rate, does not keep the fasting person alive for more than three weeks as all the protein in the body is consumed. However, a small amount of protein is used throughout the fasting period. But the whole protein is not depleted.

But if protein is used in this way and 70% of the protein in the body is used, it will be very difficult to survive. Another available source of energy at that time is fat. Fat triglycerides are stored around the adipose tissue and internal organs under the skin. Fat is a more economical fuel. Gram to gram it gives more energy i.e. nine calories energy while protein gives two calories energy. And carbohydrates give a caloric energy. In addition water is not required to store it.

Now it is the turn of fat to give energy to the body. Triglyceride which is also fat itself is broken down into glycerol and fatty acids. Glycerol goes to the liver and is used to synthesize glucose. Fatty acids are used to produce energy. Fatty acids are oxidized in the liver. I.e. it combines with oxygen. It forms a chemical called aceto acetic acid. It is delivered to various organs by the bloodstream to be used as fuel. Aceto acetic acid gives the two chemicals acetone and ketone. And when it is oxidized it gives energy along with carbon dioxide and water. It is used by almost all tissues to get energy.

In this way, energy can be obtained by breaking down carbohydrates, proteins and fats stored in the body if food was stopped during fasting. By fasting, the average person can lose 5% of his weight without any harmful effects. But drastic reductions can be fatal. And similarly, prolonged fasting for a variety of reasons can be fatal.