What Controls Metabolism? – NabtaHealth

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• What Controls Metabolism?

Article Diabetes Health Nutrition Weight

Samantha Dumas • March 14, 2022 • 5 min read

• There are many factors that control metabolism.
• Each person’s metabolism is influenced by their genes, age, illness, medications and stress.
• Metabolism is the process by which our body converts the food and drink we consume into energy.
• Metabolism is controlled by our endocrine system, which produces and releases hormones.
• Imbalances in hypothalamic and pancreatic regulation of metabolism can lead to increased risk for metabolic disorders such as diabetes type 2.

It’s tempting to dismiss or blame metabolism as being about fast or slow, weight gain or loss. The truth is metabolism lies at the core of our body’s healthy functioning. Our bodies need metabolic processes to sustain life. Metabolism keeps us alive.

What is metabolism?

Metabolism is the internal process by which our body converts the food and drink we consume into energy. This energy is stored and released as needed for use in cells. Metabolism is at the root of all work in our cells and enables other essential chemical reactions to happen. Without these chemical processes we can’t breathe, circulate blood, build and repair cells and everything else our bodies require to survive.

So how does metabolism work? 

Metabolism is a balancing act between anabolism and catabolism. Our digestive enzymes turn carbohydrates into simple sugars like glucose, fats into fatty acids, and proteins into amino acids. These nutrients are absorbed in the blood and carried through our body to cells, where they are metabolized in two finely balanced chemical processes. Catabolism is the breakdown of nutrients and the release of energy. Anabolism uses that energy for bodily processes, growth and maintenance.  

What controls metabolism? 

The whole process of metabolism is controlled by our endocrine system, a network of glands all over the body which produce and release hormones. Those hormones in turn manage most functions in our bodies, including our metabolism, reproduction, growth and development, energy levels, emotions, response to injury, stress, sexual function, and sleep.

It’s a finely tuned process. Sometimes glands produce too much or not enough of a hormone. This can lead to imbalance and health problems such as weight gain, high blood pressure, changes in mood and sleep. Many external and internal factors affect how our bodies create and release hormones. Age, medications, illness and stress can all cause hormonal imbalance. 

The hormones that regulate your metabolism, your body’s ability to break down food and create energy, are produced by your thyroid, adrenal gland, hypothalamus and pancreas. Each plays a different and complementary role in controlling and influencing your body’s metabolic health.

How is the thyroid important for metabolism?

The Thyroid is vital in regulating the metabolic processes needed for healthy growth and development, as well as regulating the body’s metabolism. The thyroid uses iodine from the food you consume to produce its two primary hormones thyroxine (T4) and triiodothyronine (T3). These are stored and secreted as needed. The link between a healthy functioning thyroid, body weight and energy expenditure is well established.

Hypothyroidism (underactive thyroid) is when the thyroid gland doesn’t release enough hormones and metabolism slows down, affecting the entire body. This is often linked with autoimmune condition Hashimoto’s disease which is an inflammation of the thyroid gland. Symptoms of hyperthyroidism in women include unusual weight gain, muscle weakness and pain, fatigue, thinning hair and constipation.

In hyperthyroidism (overactive thyroid) overproduction of hormones can lead to accelerated metabolism causing unintentional weight loss, changes in menstrual patterns, more frequent bowel movements, sweating, tachycardia (rapid heartbeat), arrhythmia (irregular heartbeat), anxiety, hair thinning and can cause Grave’s disease.

How does the adrenal gland regulate metabolism?

Adrenal or suprarenal glands sit on top of your kidneys. Adrenals produce and release cortisol (steroid) hormones and epinephrine (adrenaline) that help regulate your metabolism, immune system, blood pressure and maintain your response to stress. 

Among other important functions, cortisol helps control the body’s use of fats, proteins and carbohydrates, regulates blood pressure and increases blood sugar. Disorders related to the adrenal glands not functioning properly include Cushing syndrome, Addison’s disease, Congenital adrenal hyperplasia and Conn’s syndrome. 

Hypothalamic regulation of metabolism

Studies are increasingly demonstrating that the hypothalamus is critical in coordinating metabolism and central to energy balance. The hypothalamus region of the brain regulates metabolism by controlling food intake, energy storage and release “through the ability of neurons to sense, integrate, and respond to numerous metabolic signals. ”

How does the pancreas control metabolism?

The two glands in the pancreas are crucial to metabolism regulation, playing a key role in nutrient digestion and blood sugar control. The endocrine gland makes hormones that manage blood sugar levels; insulin lowers blood sugar and glucagon raises blood sugar levels. The exocrine gland secretes digestive enzymes crucial for breaking down carbohydrates, fats, proteins and acids in the duodenum.  

Imbalances in both hypothalamic and pancreatic regulation of metabolism can lead to increased risk for metabolic disorders such as diabetes type 2.

What are inherited metabolic disorders?

Inherited metabolic disorders are rare genetic conditions that cause a person’s metabolism to not work properly from birth. Typically caused by a family history of inherited genetic disorders or by gene changes causing a deficiency in hormones or enzymes needed for the digestion process. These deficiencies cause abnormal chemical reactions that keep the body’s metabolism from working properly, with the processes that convert food into energy and remove waste and toxins from the body compromised. Doctors have identified many different and rare disorders, each of which has varying symptoms and treatment options. 

Why is it important to understand metabolism?

Knowing how metabolism is controlled by your body’s endocrine system, and that each person’s metabolism is also influenced by their genes, age, illness, medications and stress, can help you have a better understanding of your body. 

Whenever you have weight changes (gain or loss) you can’t explain you should talk to your doctor, especially if accompanied by other possible symptoms of metabolism imbalance. 

Your doctor will run tests and advise you of treatment options and medications are available to regulate hormones. And a healthy lifestyle – staying active, eating a healthy diet and getting lots of sleep – will always have a positive impact on weight and energy levels.

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If you are concerned you may have issues with your metabolism, get tested in the privacy of your own home by ordering a blood test here.

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Metabolism – Better Health Channel

Metabolism refers to all the chemical processes going on continuously inside your body that allow life and normal functioning (maintaining normal functioning in the body is called homeostasis). These processes include those that break down nutrients from our food, and those that build and repair our body.

Building and repairing the body requires energy that ultimately comes from your food.

The amount of energy, measured in kilojoules (kJ), that your body burns at any given time is affected by your metabolism.

Achieving or maintaining a healthy weight is a balancing act. If we regularly eat and drink more kilojoules than we need for our metabolism, we store it mostly as fat.

Most of the energy we use each day is used to keep all the systems in our body functioning properly. This is out of our control. However, we can make metabolism work for us when we exercise. When you are active, the body burns more energy (kilojoules).

Two processes of metabolism

Our metabolism is complex – put simply it has two parts, which are carefully regulated by the body to make sure they remain in balance. They are:

• Catabolism – the breakdown of food components (such as carbohydrates, proteins and dietary fats) into their simpler forms, which can then be used to provide energy and the basic building blocks needed for growth and repair.
• Anabolism – the part of metabolism in which our body is built or repaired. Anabolism requires energy that ultimately comes from our food. When we eat more than we need for daily anabolism, the excess nutrients are typically stored in our body as fat.

Metabolic rate

Your body’s metabolic rate (or total energy expenditure) can be divided into three components, which are:

• Basal metabolic rate (BMR) – even at rest, the body needs energy (kilojoules) to keep all its systems functioning correctly (such as breathing, keeping the heart beating to circulate blood, growing and repairing cells and adjusting hormone levels). The body’s BMR accounts for the largest amount of energy expended daily (50–80 per cent of your daily energy use).
• Thermic effect of food (also known as thermogenesis) – your body uses energy to digest the foods and drinks you consume and also absorbs, transports and stores their nutrients. Thermogenesis accounts for about 5–10 per cent of your energy use.
• Energy used during physical activity – this is the energy used by physical movement and it varies the most depending on how much energy you use each day. Physical activity includes planned exercise (like going for a run or playing sport) but also includes all incidental activity (such as hanging out the washing, playing with the dog or even fidgeting!).

Based on a moderately active person (30–45 minutes of moderate-intensity physical activity per day), this component contributes 20 per cent of our daily energy use.

Basal metabolic rate (BMR)

The BMR refers to the amount of energy your body needs to maintain homeostasis.

Your BMR is largely determined by your total lean mass, especially muscle mass, because lean mass requires a lot of energy to maintain. Anything that reduces lean mass will reduce your BMR.

As your BMR accounts for so much of your total energy consumption, it is important to preserve or even increase your lean muscle mass through exercise when trying to lose weight.

This means combining exercise (particularly weight-bearing and resistance exercises to boost muscle mass) with changes towards healthier eating patterns rather than dietary changes alone as eating too few kilojoules encourages the body to slow the metabolism to conserve energy.

Maintaining lean muscle mass also helps reduce the chance of injury when training, and exercise increases your daily energy expenditure.

An average man has a BMR of around 7,100 kJ per day, while an average woman has a BMR of around 5,900 kJ per day. Energy expenditure is continuous, but the rate varies throughout the day. The rate of energy expenditure is usually lowest in the early morning.

Factors that affect our BMR

Your BMR is influenced by multiple factors working in combination, including:

• Body size – larger adult bodies have more metabolising tissue and a larger BMR.
• Amount of lean muscle tissue – muscle burns kilojoules rapidly.
• Amount of body fat – fat cells are ‘sluggish’ and burn far fewer kilojoules than most other tissues and organs of the body.
• Crash dieting, starving or fasting – eating too few kilojoules encourages the body to slow the metabolism to conserve energy. BMR can drop by up to 15 per cent and if lean muscle tissue is also lost, this further reduces BMR.
• Age – metabolism slows with age due to loss of muscle tissue, but also due to hormonal and neurological changes.
• Growth – infants and children have higher energy demands per unit of body weight due to the energy demands of growth and the extra energy needed to maintain their body temperature.
• Gender – generally, men have faster metabolisms because they tend to be larger.
• Genetic predisposition – your metabolic rate may be partly decided by your genes.
• Hormonal and nervous controls – BMR is controlled by the nervous and hormonal systems. Hormonal imbalances can influence how quickly or slowly the body burns kilojoules.
• Environmental temperature – if temperature is very low or very high, the body has to work harder to maintain its normal body temperature, which increases the BMR.
• Infection or illness – BMR increases because the body has to work harder to build new tissues and to create an immune response.
• Amount of physical activity – hard-working muscles need plenty of energy to burn. Regular exercise increases muscle mass and teaches the body to burn kilojoules at a faster rate, even when at rest.
• Drugs – like caffeine or nicotine, can increase the BMR.
• Dietary deficiencies – for example, a diet low in iodine reduces thyroid function and slows the metabolism.

Thermic effect of food

Your BMR rises after you eat because you use energy to eat, digest and metabolise the food you have just eaten. The rise occurs soon after you start eating, and peaks two to three hours later.

This rise in the BMR can range between two per cent and 30 per cent, depending on the size of the meal and the types of foods eaten.

Different foods raise BMR by differing amounts. For example:

• Fats raise the BMR 0–5 per cent.
• Carbohydrates raise the BMR 5–10 per cent.
• Proteins raise the BMR 20–30 per cent.
• Hot spicy foods (for example, foods containing chilli, horseradish and mustard) can have a significant thermic effect.

Energy used during physical activity

During strenuous or vigorous physical activity, our muscles may burn through as much as 3,000 kJ per hour. The energy expenditure of the muscles makes up only 20 per cent or so of total energy expenditure at rest, but during strenuous exercise, it may increase 50-fold or more.

Energy used during exercise is the only form of energy expenditure that we have any control over.

However, estimating the energy spent during exercise is difficult, as the true value for each person will vary based on factors such as their weight, age, health and the intensity with which each activity is performed.

Australia has physical activity guidelinesExternal Link that recommend the amount and intensity of activity by age and life stage. It’s important for our overall health that we limit our time being sedentary (sitting or lounging around) and make sure we get at least 30 minutes of moderate-intensity physical activity every day.

As a rough guide:

• Moderate exercise means you can talk while you’re exercising, but you can’t sing.
• Vigorous exercise means you can’t talk and exercise at the same time.

Muscle tissue has a large appetite for kilojoules. The more muscle mass you have, the more kilojoules you will burn.

People tend to put on fat as they age, partly because the body slowly loses muscle. It is not clear whether muscle loss is a result of the ageing process or because many people are less active as they age. However, it probably has more to do with becoming less active. Research has shown that strength and resistance training can reduce or prevent this muscle loss.

If you are over 40 years of age, have a pre-existing medical condition or have not exercised in some time, see your doctor before starting a new fitness program.

Hormonal disorders of metabolism

Hormones help regulate our metabolism. Some of the more common hormonal disorders affect the thyroid. This gland secretes hormones to regulate many metabolic processes, including energy expenditure (the rate at which kilojoules are burned).

Thyroid disorders include:

• Hypothyroidism (underactive thyroid) – the metabolism slows because the thyroid gland does not release enough hormones. A common cause is the autoimmune condition Hashimoto’s disease. Some of the symptoms of hypothyroidism include unusual weight gain, lethargy, depression and constipation.
• Hyperthyroidism (overactive thyroid) – the gland releases larger quantities of hormones than necessary and speeds the metabolism. The most common cause of this condition is Graves’ disease. Some of the symptoms of hyperthyroidism include increased appetite, weight loss, nervousness and diarrhoea.

Genetic disorders of metabolism

Our genes are the blueprints for the proteins in our body, and our proteins are responsible for the digestion and metabolism of our food.

Sometimes, a faulty gene means we produce a protein that is ineffective in dealing with our food, resulting in a metabolic disorder. In most cases, genetic metabolic disorders can be managed under medical supervision, with close attention to diet.

The symptoms of genetic metabolic disorders can be very similar to those of other disorders and diseases, making it difficult to pinpoint the exact cause. See your doctor if you suspect you have a metabolic disorder.

Some genetic disorders of metabolism include:

• Fructose intolerance – the inability to break down fructose, which is a type of sugar found in fruit, fruit juices, sugar (for example, cane sugar), honey and certain vegetables.
• Galactosaemia – the inability to convert the carbohydrate galactose into glucose. Galactose is not found by itself in nature. It is produced when lactose is broken down by the digestive system into glucose and galactose. Sources of lactose include milk and milk products, such as yoghurt and cheese.
• Phenylketonuria (PKU) – the inability to convert the amino acid phenylalanine into tyrosine. High levels of phenylalanine in the blood can cause brain damage. High-protein foods and those containing the artificial sweetener aspartame must be avoided.

Where to get help

• Your doctor
• Dietitians Association of Australia Tel. 1800 812 942 or find a dietitian near youExternal Link

Metabolism and nutrition – what is it, definition and answer

Metabolism is one of the main signs of living things, by which it can be distinguished from non-living. Metabolism or metabolism includes a variety of processes of synthesis, transformation and oxidation (destruction) of substances. Nutrition and digestion is the first important stage of metabolism.

External metabolism

The external stage of metabolism consists of the processes of moving substances from the external environment into the internal environment of the body. It consists of three processes: nutrition, respiration and excretion.

Nutrition provides the body with nutrients as a result of digestion, which, after certain preparation, will act as a building material and energy source.

Digestion consists of several stages:

• Mechanical treatment in the oral cavity, its moisturizing and processing with digestive juices,

• Absorption of elementary structures and blood and lymph.

Respiration is the process of oxygen supply to the body, oxidation of organic substances with the help of it and the release of energy, which will be used to support life processes.

Isolation is the process of removing harmful or unnecessary substances from the body from the internal environment to the external environment.

Main ways of metabolism of bioorganic substances

Metabolism consists of two opposite processes – plastic and energy exchanges.

• Energy metabolism – a set of decomposition reactions of substances that occur with the release of energy. Proteins are broken down into amino acids during digestion, carbohydrates into glucose, and fats into glycerol and fatty acids. During the oxidation (decay) of substances, energy is released, which is the energy of the bonds of ATP molecules.

• Plastic metabolism – a set of reactions of synthesis of substances, accompanied by energy consumption. Those structural elements that appeared during the breakdown of proteins, fats and carbohydrates enter the internal environment of the body and go to the synthesis of their own organic substances. The processes of their creation require energy stored in the bonds of ATP molecules. After fulfilling their function, their own organic substances also undergo decay in energy metabolism.

At the final stage of energy metabolism, organic substances will be broken down into carbon dioxide, water and urea, and removed through the excretory organs.

Enzymes are biological catalysts of protein nature, without which no metabolic process can do. Each process will have its own unique enzyme. The formation of enzymes and their action is controlled by genes.

Metabolic disorders

In the human body, as, indeed, in other living beings, two mutually balanced processes simultaneously flow: everything in the body is constantly destroyed with the formation of energy and everything is constantly restored due to the consumption of food, so apparently no changes absolutely not. The balance of these two processes is the essence of the so-called metabolism.

The metabolism in the human body is considered normal when the processes of energy production and its recovery are in perfect harmony with each other. But often it comes with some predominance of one of them.

If in some respect processes of disintegration and production of energy predominate, they say about such people: “not a horse’s fodder”… Such people lose weight.

If, in some respect, accumulative, building processes predominate, then the opposite phenomenon takes place… Such people are overweight.

Metabolism, like everything else in the body, is regulated by the nervous system; so what is the organization of the tone of the nerve regulatory centers, such is the state of the organism. Therefore, in order to transfer the organism as a whole from one stable state to another, it is necessary to steadily change the tone of individual centers of the brain.

The regulation of metabolism in the human body is mainly occupied by a part of the brain called the “hypothalamus”. Two departments were found in it: ergotic (Greek ergon – work) – it regulates the rate of energy production, and trophic (Greek trophe – food, nutrition) – it regulates construction, restoration, accumulation processes.

If for some reason the tone of the ergotic department of the hypothalamus is increased, then the person loses weight. If, for some reason, the tone of the trophic section is increased, the processes of accumulation and deposition are intensified … So, the regulatory shift mentioned above is the so-called metabolic disorder.

So, the regulation of metabolic processes is carried out directly by the central and autonomic nervous system or hormonally. Any disease is accompanied by

a violation of metabolic processes in the body, which is especially clearly manifested in disorders of the functions of the nervous system and endocrine glands. The basal metabolism increases in diseases associated with an increase in the functions of the thyroid gland, and decreases in diseases caused by insufficient function of this gland, as well as with a decrease in the function of the pituitary gland, adrenal glands, gonads, and with general starvation.