^

The simple ABCs of metabolism

, medical expert
Last reviewed: 04.07.2025
Fact-checked
х

All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.

We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.

If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.

The basis of metabolism is the food we eat. It is difficult to even think about what would happen if we did not receive fuel in the form of food. That is, we did not receive energy for life. How does the metabolic system work in the body?

How does the metabolic system work?

When food begins to digest, the body divides it into very small structures: amino acids, glucose, fats. Then the food is easier to digest. With the blood, these tiny molecules of useful substances are carried throughout the body. Organs and tissues feed on these substances, process them and receive energy for work.

Proteins are converted into amino acids, fats into fatty acids, and all of this is converted into glucose (we call it "blood sugar"). Glucose interacts with oxygen and we get energy for the body's cells.

If we explain this whole system as simply as possible, it turns out that metabolism is the name of a whole large process, when food is divided into particles, oxidized with the help of oxygen and gives us energy for life.

What is glucose and how does it work?

Glucose is one of the substances that the body converts from food during its digestion. When fructose and glucose molecules combine, another element is obtained - sucrose. This element can easily and quickly turn back into glucose.

The sugars in our blood are stored in a substance called glycogen. It acts as a container for glucose, ensuring its storage in the muscles and liver.

Glucose compounds can be released from there as energy for life when the blood sugar level drops significantly. For example, when a person needs to move suddenly and quickly, glucose is released from the liver and muscles as energy for these movements.

How to determine glucose levels?

Glucose is a substance found in the blood that supplies energy to cells, primarily brain cells.

Without glucose in the blood, the brain cannot function properly. When there is not enough glucose, doctors may diagnose hypoglycemia.

You can tell if you have low blood glucose (or if it drops immediately after eating) by these symptoms.

  • Unpleasant sensations in the stomach area
  • Nausea
  • Weakness
  • Frequent and strong heartbeat
  • Cold sweat
  • Irritability
  • Confused thoughts
  • Memory lapses

All these symptoms may mean that the brain is reacting negatively to stress. The brain centers send a signal to the hormone norepinephrine, which has the property of increasing the level of stress in the blood even more. This is done by the adrenal glands.

This is the body's preparation for running away. Such preparation is a legacy of ancient times, when a man ran away from a mammoth or a wild bear. Now we are not running anywhere, but the hormonal explosion is still present. First of all, the sugar level increases, which gives energy for running or jumping.

When blood glucose levels are very high

...this threatens a person with diabetes. At the symptom level it looks like this.

  • Weakness, lethargy, especially after lunch
  • A tendency to fall asleep during the day at inopportune moments
  • Difficulty remembering
  • Feeling of increased anxiety

These symptoms are an indication that glucose levels and the level of the hormone serotonin in the brain are significantly elevated.

But you should know that both high and low levels of glucose in the body provoke damage to the brain or the worst consequences in the form of death.

How can you regulate your glucose levels?

We already know that oxygen and glucose are needed for stable brain function. To control the level of glucose in the blood, the body has provided special mechanisms.

Insulin and glucogen are also involved in this process. The role of insulin is to reduce glucose levels by moving it into so-called fat cells. There, glucose is burned and converted into energy.

The role of glucogen is to increase blood glucose levels or to normalize blood glucose levels by preventing glucose from increasing. This occurs when liver cells and muscle cells are stimulated by glucogen.

Thus, glucogen is destroyed, and glucose cells move from the liver into the blood. Then the blood sugar level increases.

Action of insulin and glucogen

It is not only important that the blood glucose level can decrease or increase. It is important how quickly and regularly this happens. Glucose level jumps provoke an increase in the level of glucagon and insulin. And then the woman can start to gain weight. And then a strange thing happens.

As weight increases, glucagon and insulin can no longer control glucose levels as well as they once did, and then glucose can rise and fall uncontrollably.

This can lead to low blood sugar (hypoglycemia) or too high glucose levels alternating with too low. As additional processes, glucose intolerance and diabetes begin.

How can hormone levels affect weight gain?

We often observe a brutal appetite during menstruation or a week before it. Women have a special craving for chocolate in all its forms - from sweets to cakes.

This is normal: during stressful situations, a person needs glucose.

What happens to the ovarian hormones that cause us to lose our ability to control ourselves in food during the second half of the cycle and as we approach menopause?

Glucose plays a huge role in this, or rather, its amount in the blood. And insulin, which determines the intensity of glucose entering the blood. But it happens that the body does not perceive glucose. More about the role of insulin and how it affects the level of glucose in the body.

Insulin dependence

What is insulin for humans? It is a hormone that helps strengthen tissues and activate metabolism, as well as control the accumulation of fatty tissue. It does this by controlling glucose levels.

If there is not enough insulin in the body (and it supplies blood to the body's cells), a person will feel very bad. Insulin helps cells accumulate energy and it also helps to accumulate fat (the process is called lipogenesis).

It turns out that the ratio of muscle tissue and fats in the body changes, as well as their breakdown due to insulin. The more insulin, the more actively insulin stimulates them. This means that muscle cells are no longer as active in burning fat. And the person gains weight.

That is, with an excess of insulin, a woman is guaranteed to gain excess weight, especially if she had a tendency to be overweight before.

How to recognize excess insulin in the body?

It becomes especially high as a woman gets older. Insulin levels can increase with each passing year, so be on the lookout and check them.

Insulin in large quantities can be recognized by these signs.

  • Menu with a lot of carbohydrates (especially sweets and flour)
  • Constant and prolonged stress – this increases the level of the stress hormone cortisol, which suppresses the production of glucose and inhibits the production of insulin
  • Suppression of ovarian function, which reduces the level of the hormone estradiol, which is produced by the ovaries. This causes the level of the male hormone testosterone to increase, which contributes to the deposition of fat in the body
  • Restless and anxious sleep
  • Elevated levels of the thyroid hormone DHEA, while the thyroid gland is weak in performing its role in producing hormones
  • Hypodynamia, or lack of physical activity

Increased glucose levels that are difficult to control due to a lack of hormones that perform this role.

If you notice visible symptoms of insulin deficiency, be sure to see an endocrinologist for examination. Be healthy!

You are reporting a typo in the following text:
Simply click the "Send typo report" button to complete the report. You can also include a comment.