The metabolism
What is the metabolism?
When you eat, you gain building blocks for body maintenance as well as energy for using those building blocks. Your metabolism is the energy burning process that takes place constantly within your working body cells.
You are constantly burning energy
Your cells are burning energy the entire time – even if you are lying completely still. The amount of energy burned by your body when it is resting is called the resting metabolism, which you might want to calculate by means of the following table: Identify the correct formula in the list below, depending on your sex and age. Insert your bodyweight in kilos where is says “kg” and use a calculator to calculate your resting metabolism.
The number you reach is the amount of energy in kilo-calories (kcal) needed by your body for each 24 hours – just to survive.
You are constantly burning energy
Your cells are burning energy the entire time – even if you are lying completely still. The amount of energy burned by your body when it is resting is called the resting metabolism, which you might want to calculate by means of the following table: Identify the correct formula in the list below, depending on your sex and age. Insert your bodyweight in kilos where is says “kg” and use a calculator to calculate your resting metabolism.
The number you reach is the amount of energy in kilo-calories (kcal) needed by your body for each 24 hours – just to survive.
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Sex
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Age
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Calculation of resting metabolism:
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Women
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0 - 3
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(0.0244 x kg – 0.13) x 239
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4 - 10
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(0.085 x kg + 2.03) x 239
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11 - 18
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(0.056 x kg + 2.90) x 239
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19 - 30
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(0.0615 x kg + 2.08) x 239
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31 - 60
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(0.0364 x kg + 3.47) x 239
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61 - 75
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(0.0386 x kg + 2.88) x 239
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0ver 75
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(0.0410 x kg + 2.61) x 239
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Men
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0 - 3
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(0.249 x kg – 0.13) x 239
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4 - 10
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(0.095 x kg + 2.11) x 239
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11 - 18
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(0.074 x kg + 2.75) x 239
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19 - 30
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(0.064 x kg + 2.84) x 239
| |
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31 - 60
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(0.0485 x kg + 3.67) x 239
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61 - 75
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(0.0499 x kg + 2.93) x 239
| |
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0ver 75
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(0.035 x kg + 3.43) x 239
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In muscle cells, the level of metabolism is at its highest, whereas the metabolism in fat cells is next to nothing. When you move, you need more energy for your muscle cells.
Building up your body requires energy
Your cells are in need of energy to build up new cell components once the old ones are worn out. As an example, they build up proteins by means of amino acids. Amongst other things, proteins are found in skin and muscles. The cells get the energy for performing such construction tasks by metabolising other matters: glucose, fat and amino acids. Their preferred source of energy is carbohydrate in the form of glucose; however, most of them are also able to use fat. Amino acids are only used as a last resort. Brain cells rely entirely on glucose as a source of energy, making it very important that the blood always contains enough glucose to cover the needs of the brain.
Your cells are in need of energy to build up new cell components once the old ones are worn out. As an example, they build up proteins by means of amino acids. Amongst other things, proteins are found in skin and muscles. The cells get the energy for performing such construction tasks by metabolising other matters: glucose, fat and amino acids. Their preferred source of energy is carbohydrate in the form of glucose; however, most of them are also able to use fat. Amino acids are only used as a last resort. Brain cells rely entirely on glucose as a source of energy, making it very important that the blood always contains enough glucose to cover the needs of the brain.
Storage capacities within the body
The body is able to store glucose within the liver and in fat within the fat tissues. The size of the glucose storage is relatively small; it is only able to store sufficient glucose for about a day of energy consumption. Within the fat layer, however, enough fat for around 2 months may be stored.
As mentioned earlier, the body does not like using amino acids as a source of energy because they are mainly needed to build up muscles, skin and other structures within the body. If it becomes necessary – because of a longer period of hunger – the body will start metabolising these structures in order to get the amino acids out of there again. This process will mainly cause muscles to deteriorate and later, inner organ proteins will start to be metabolised, eventually causing death.
The body is able to store glucose within the liver and in fat within the fat tissues. The size of the glucose storage is relatively small; it is only able to store sufficient glucose for about a day of energy consumption. Within the fat layer, however, enough fat for around 2 months may be stored.
As mentioned earlier, the body does not like using amino acids as a source of energy because they are mainly needed to build up muscles, skin and other structures within the body. If it becomes necessary – because of a longer period of hunger – the body will start metabolising these structures in order to get the amino acids out of there again. This process will mainly cause muscles to deteriorate and later, inner organ proteins will start to be metabolised, eventually causing death.
The two metabolism phases
The metabolism is divided into two phases:
The absorption phase takes place shortly after a meal and for the next approx. 4 hours. A lot of nutrients in the form of glucose, fats and amino acids are transported from the food into the blood. The cells will absorb the nutrients and store those matters not needed immediately for later use.
The post-absorption phase begins around 4 hours after a meal. Now, the body is about to run out of readily available nutrients in the blood and starts using the stored nutrients instead.
The fat deposits are mobilised as a source of energy in order to economise on glucose in the blood. It is important to ensure that the glucose level in the blood does nor surpass a certain lower level because this would cause a lack of fuel to the brain. A low glucose level leads to symptoms such as tiredness and concentration problems. In very bad cases, you might loose consciousness.
The metabolism is divided into two phases:
The absorption phase takes place shortly after a meal and for the next approx. 4 hours. A lot of nutrients in the form of glucose, fats and amino acids are transported from the food into the blood. The cells will absorb the nutrients and store those matters not needed immediately for later use.
The post-absorption phase begins around 4 hours after a meal. Now, the body is about to run out of readily available nutrients in the blood and starts using the stored nutrients instead.
The fat deposits are mobilised as a source of energy in order to economise on glucose in the blood. It is important to ensure that the glucose level in the blood does nor surpass a certain lower level because this would cause a lack of fuel to the brain. A low glucose level leads to symptoms such as tiredness and concentration problems. In very bad cases, you might loose consciousness.
The two main metabolism actors: Insulin and glucagon
These two metabolism actors are hormones that are produced and released from the pancreas located just below the stomach. Insulin is active during the absorption phase, whereas glucagon is active during the post-absorption phase. These two hormones have opposite effects.
These two metabolism actors are hormones that are produced and released from the pancreas located just below the stomach. Insulin is active during the absorption phase, whereas glucagon is active during the post-absorption phase. These two hormones have opposite effects.
Insulin makes the cells absorb and store nutrients
Insulin is released once the level of glucose contained within the blood increases following a meal. Many of the body cells are unable to absorb nutrients from the blood on their own, and insulin takes on the role as a kind of key that unlocks the cells to let in the nutrients. At the same time, insulin tells the cells to store any excess nutrients and avoid eating up their storage just yet. Only brain cells, lever cells and working muscle cells need no insulin to absorb glucose.
You might have heard of insulin from people with diabetes. Their pancreas no longer produces insulin, causing the need for those people to inject the insulin into their bloodstream. If they do not supply insulin, the cells would hunger despite plenty of nutrients being available within the blood.
Insulin is released once the level of glucose contained within the blood increases following a meal. Many of the body cells are unable to absorb nutrients from the blood on their own, and insulin takes on the role as a kind of key that unlocks the cells to let in the nutrients. At the same time, insulin tells the cells to store any excess nutrients and avoid eating up their storage just yet. Only brain cells, lever cells and working muscle cells need no insulin to absorb glucose.
You might have heard of insulin from people with diabetes. Their pancreas no longer produces insulin, causing the need for those people to inject the insulin into their bloodstream. If they do not supply insulin, the cells would hunger despite plenty of nutrients being available within the blood.
Glucagon makes the cells release stored nutrients
Once the post-absorption phase sets in and the level of nutrients in the blood decreases, glucagon is released. This hormone tells the cells to release stored glucose and fat, allowing it to enter the blood and start functioning as a source of energy. It also tells the lever to start producing glucose by means of other matters such as amino acids.
During the post-absorption phase you will often start feeling hungry again because your blood sugar level will start to decrease – and then the circle begins all over again.
Once the post-absorption phase sets in and the level of nutrients in the blood decreases, glucagon is released. This hormone tells the cells to release stored glucose and fat, allowing it to enter the blood and start functioning as a source of energy. It also tells the lever to start producing glucose by means of other matters such as amino acids.
During the post-absorption phase you will often start feeling hungry again because your blood sugar level will start to decrease – and then the circle begins all over again.
