Metabolism: Definition, Process, Foods, Disorders, Types, Tests

Understanding metabolism is pivotal for overall health and wellness. Often viewed as the engine of our body, metabolism encompasses the processes that convert what we eat into energy. 

Factors like age, genetics, and lifestyle play crucial roles in determining its efficiency. Whether you’re curious about how certain foods impact metabolism or want actionable advice on optimizing them, this article aims to offer clear insights. 

With a blend of technical details and practical tips, we’ll explore the metabolism world, ensuring you walk away more informed and empowered.

What is metabolism?

Metabolism, at its core, refers to the chemical processes occurring within our bodies to maintain life. Imagine it as a behind-the-scenes worker, tirelessly converting the food we consume into energy [1]. 

This energy sustains vital functions, from powering our brain to supporting physical activity. Broadly, metabolism splits into two categories: catabolism and anabolism [1].

Catabolism breaks down molecules to produce energy. For instance, when our bodies break down food to release energy, that’s catabolism at work. 

On the other hand, anabolism uses this energy to build and repair cells, allowing growth and maintaining body tissues. Think of it like constructing a building: the energy is the workforce, and the building is the cell being repaired or constructed.

Both these processes work hand-in-hand, ensuring that our bodies function effectively and maintain a balance. Remember, metabolism is unique for everyone, influenced by factors we’ll discuss further in this article. 

It’s not just about how fast or slow one burns calories; it’s about the overall health and balance of our internal systems.

What are the 3 metabolic processes?

When we discuss metabolism, it’s like talking about the body’s personal power plant. This power plant is constantly at work, ensuring we have enough energy to function, even when we’re resting. Let’s break down the primary components of the metabolic process.

1. Basal Metabolic Rate (BMR)

This refers to the energy our bodies require at rest, essentially covering essential functions like breathing, blood circulation, and cell growth [2]. 

Several factors, including age, gender, muscle mass, and genetics, can influence your BMR. Curious about your BMR? There are calculators, that provide an estimate based on personal details.

2. Thermogenesis

After eating a meal, you might have felt warmer. That’s because of thermogenesis, the process where our bodies produce heat. This accounts for the energy used to digest, absorb, and transport nutrients. 

Spicy foods, caffeine, and certain proteins can boost this effect, slightly increasing calorie burn [3].

3. Energy expenditure

Beyond the energy used at rest, our bodies consume energy during physical activities. Whether you’re walking, lifting weights, or even typing, you’re expending energy.

The type and duration of activity can determine how much energy you use. Want to optimize this? Consider activities that use multiple muscle groups, like swimming or full-body workouts.

Understanding these processes gives insight into how our bodies function. While it might sound complex, the take-home message is simple: our bodies are constantly at work, converting food into energy, maintaining vital functions, and supporting our activities. 

energy expenditure

What are the different types of metabolism?

The human body efficiently converts food into energy and building blocks. The processes governing these conversions are categorized under metabolism. 

Let’s explore the distinct metabolic pathways, each responsible for handling a specific type of nutrient.

Carbohydrate metabolism

Carbohydrates, found abundantly in foods like bread, rice, and fruits, are the body’s primary energy source. Once consumed, these carbohydrates are converted into glucose. 

Glucose then enters our bloodstream, and with the help of insulin, fuels our cells. Any excess glucose gets stored in the liver and muscles as glycogen for future energy needs. 

When energy is required, and glucose is low, glycogen is converted back to glucose to meet the demand.

Protein metabolism

Proteins, essential for growth and repair, are broken down into amino acids through digestion. 

Not all amino acids are equal. Essential ones must be obtained from diet, while the body can produce others.

Fat metabolism

Fats serve as a secondary energy source and are essential for absorbing certain vitamins and producing hormones. When consumed, fats are broken down into fatty acids and glycerol. 

These components can be burned immediately for energy or stored in fat cells for later use. When glucose levels are low, the body taps into these stored fats for energy.

Nucleic acid metabolism

Nucleic acids, namely DNA and RNA, are vital for storing and transmitting genetic information [4]. 

Their metabolism involves the synthesis of new nucleotides and the breakdown and recycling of old ones. 

These processes ensure our cells can grow, divide, and function optimally.

Understanding these metabolic pathways offers insights into how our bodies use and store energy. 

It emphasizes the importance of a balanced diet, as different nutrients play unique and vital roles in our overall health.

11 Factors affecting your metabolism

Ever wonder why some people seem to burn off a dessert effortlessly, while others claim to gain weight just by looking at a piece of cake? The answer lies in the differences in individual metabolisms. 

Metabolism isn’t just a singular process; a blend of factors influences it, some within our control and others not so much. Let’s explore what makes this metabolic orchestra so unique for everyone.

1. Age

As we age, our body tends to lose muscle mass and gain fat, which results in a slower metabolism [5]. It is essential to maintain muscle mass through resistance training, especially as we age, because muscle burns more calories than fat.

2. Genetics

Yes, the genetic code you inherited from your parents plays a role. Some people naturally have a faster metabolism, while others may have to work a bit harder to keep their metabolic rate up. Recent studies suggest that our genes can influence how we store fat and how our bodies utilize energy [6].

3. Gender

Generally, men have more muscle and less body fat than women of the same age and weight. Consequently, men burn more calories. 

Women, especially during their reproductive years, naturally store more fat in preparation for child-bearing, which can affect metabolic rate.

4. Body composition and size

Larger bodies, or those with more muscle mass, burn more calories, even at rest. Muscle is metabolically active, meaning it requires energy even when you’re not moving. Hence, increasing muscle mass can help boost metabolism.

5. Physical activity

The more active you are, the more calories you burn. Regular physical activity, especially muscle-strengthening exercises, can significantly influence your metabolic rate. From walking to intense gym sessions, every movement counts.

6. Hormonal factors

Hormones are chemical messengers that influence many bodily functions, including metabolism. Thyroid hormones play a pivotal role. 

If the thyroid produces too much thyroxine, it can cause hyperthyroidism, leading to a fast metabolism. Conversely, too little can result in hypothyroidism, slowing metabolism down [7]. 

hormone factors

7. Environmental factors

Believe it or not, external factors like temperature can influence metabolism [8]. When it’s cold, our bodies work harder to maintain body temperature, slightly boosting metabolism. 

Similarly, hot weather or increased humidity can elevate the metabolic rate as the body works to cool itself.

8. Dietary habits

What we eat, and even when we eat, can affect metabolism. Consuming small, frequent meals can keep metabolism active. 

Similarly, certain foods, like those rich in protein, require more energy to digest, offering a slight metabolic boost.

9. Stress

Prolonged stress can cause imbalances in hormones, which can result in a decrease in metabolic functions. Finding ways to manage stress, whether through relaxation techniques or physical activity, can help keep metabolism in check.

10. Medications

Some medications, including certain antidepressants and antipsychotics, can influence metabolic rate. 

If you’re concerned about how your medications might be affecting your metabolism, it’s a good idea to consult with a healthcare professional.

11. Health conditions

Beyond thyroid disorders, conditions like Cushing’s syndrome and polycystic ovary syndrome (PCOS) can influence metabolism. Weight gain and changes in energy processing can result from both states.

Recognizing these factors can help us make informed decisions about our health and wellness. 

While some factors are beyond our control, understanding our metabolic makeup empowers us to take actionable steps where possible. 

Whether it’s through diet, exercise, or stress management, there are always avenues to explore for metabolic health.

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How can foods influence your metabolism?

Every meal we consume acts as a regulatory signal for our metabolism. Some foods give it a nudge upwards, while others can cause a bit of a slowdown. 

Making educated choices can, over time, influence how efficiently our bodies convert food into energy. Here’s a detailed look at these foods and their effects.

Metabolism-boosting foods

1.  Protein

Consuming foods like lean meats, eggs, legumes, and dairy products can temporarily raise your metabolic rate. This is due to the thermic effect of food, where the body uses energy to digest and process. Plus, they can make you feel fuller, potentially reducing overall calorie intake.

2. Green tea

Packed with antioxidants, green tea can elevate metabolic rate and increase the amount of fat your body burns.

3. Capsaicin 

This compound not only adds heat to your meals but can also slightly enhance metabolism and fat oxidation.

4. Whole grains

Choosing brown rice over white or quinoa over processed pasta means your body works harder during digestion, slightly raising metabolism.

5. Fatty fish

Salmon and mackerel are rich in omega-3 fatty acids, which reduce inflammation and balance blood sugar levels, promoting metabolic health.

Foods that may slow down metabolism

1.  Excess sugars and fats

Limiting processed foods, sugary beverages, and desserts is vital in preventing weight gain and a slow metabolism caused by excessive consumption of sugars and saturated fats.

2. Refined carbs

Refined carbohydrates, like white bread and pastries, can lead to rapid fluctuations in blood sugar levels, resulting in changes in energy levels and metabolic rate.

What to consume in moderation

1. Alcohol

While an occasional drink might not be harmful, excessive alcohol consumption can decrease metabolic rate and promote weight gain. It can disrupt the balance of hormones involved in metabolic regulation and can decrease the body’s ability to burn fat.

2. Caffeine

Moderate coffee consumption can boost metabolism. Coffee contains a stimulant that temporarily elevates metabolic rate. However, excessive caffeine intake can lead to dehydration and sleep disruption, negatively affecting metabolism. 

Furthermore, relying on coffee too much can lead to insomnia, ultimately slowing down metabolism.

What is the role of water in metabolism

Staying hydrated is essential for a smooth-running metabolism. Water aids in every cellular process, including those that burn calories. 

Drinking sufficient amounts can temporarily boost metabolic rate, and staying hydrated helps your body efficiently carry out metabolic processes.

Making informed food choices goes beyond just counting calories. It’s about understanding how specific foods and drinks interact with the unique machinery of our bodies. By optimizing these choices, we set the stage for better metabolic health and overall well-being.

What are the different types of metabolic disorders?

Metabolic disorders, though varied in nature, all involve disruptions in the body’s typical processes of breaking down and using nutrients. 

These disorders can have profound health implications. Let’s delve into some essential types and their specifics:

Inborn Errors of Metabolism (IEM)

These are hereditary conditions resulting from enzyme deficiencies that disrupt metabolic processes [9]. Examples include:

A.  Phenylketonuria (PKU)

A deficiency in processing phenylalanine, an amino acid, leading to potential intellectual disabilities [10].

B. Galactosemia

An inability to metabolize the sugar galactose, commonly found in milk. If left untreated, it can cause liver damage and other severe complications [11].

Metabolic syndrome

Metabolic syndrome

This isn’t a disease but a cluster of conditions that often occur together, increasing the risk of heart disease, stroke, and type 2 diabetes

Symptoms include high blood pressure, high blood sugar, excess body fat around the waist, and abnormal cholesterol levels. Key risks encompass obesity, inactivity, and genetics.


This is a group of diseases that result in high blood sugar (glucose) levels. Diabetes affects how your body uses blood sugar, crucial for health since it’s an essential source of energy for cells. 

The connection to metabolism is direct: our bodies break down carbohydrates from food into sugar, which cells then use for energy.

A. Type 1 diabetes

The body doesn’t produce insulin, a hormone that regulates blood sugar. It’s usually diagnosed in children and young adults.

B. Type 2 diabetes

The body either resists the effects of insulin or doesn’t produce enough to maintain normal blood sugar levels. It’s more common in adults but can occur at any age.

Awareness and understanding of these disorders are crucial. If you or a loved one displays symptoms of any metabolic disorder, it’s essential to consult a medical professional for a thorough evaluation and guidance.

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How can you increase your metabolism?

Metabolism, in essence, is the process by which our bodies convert what we eat and drink into usable energy. 

A more efficient metabolic rate can benefit energy production, weight management, and overall health. Here are some actionable strategies to help give your metabolism a boost:

1. Stay active

Physical activity, whether it’s cardio, strength training, or even just walking, can increase your metabolic rate both during the activity and afterward.

Strength training, in particular, builds muscle mass, and muscle burns more calories at rest compared to fat.

2. Prioritize protein

Incorporating more protein into your diet can induce the thermic effect of food, a phenomenon where the body burns more calories digesting food. Protein-rich meals can also help you feel full, assisting in weight management.

3. Get enough sleep

Poor sleep can interfere with the body’s hunger hormones and could reduce your resting metabolic rate. Aim for 7-9 hours of quality sleep per night.

4. Stay hydrated

Drinking water and other low-calorie drinks can temporarily boost metabolism. Cold water might also make your body use more energy to heat it to body temperature.

5. Eat small, frequent meals

Instead of three large meals, consider eating smaller amounts more frequently throughout the day. This can prevent blood sugar drops and keep your metabolism active.

6. Limit stress

Chronic stress can lead to hormonal imbalances that might slow down your metabolism. Find stress-reducing techniques that work for you, be it meditation, reading, or a hobby.

7. Avoid crash diets

Extremely low-calorie diets can decrease your basal metabolic rate and harm muscle tissue. It’s always recommended to follow a balanced diet and consult with a nutritionist for personalized guidance.

8. Stay warm

Cold environments can slow down the calorie-burning process. While the body does burn calories to warm itself, prolonged exposure to cold might not be beneficial for metabolic efficiency.

How do you assess and test your metabolism?

Understanding one’s metabolic health is crucial for optimal well-being. Various tests are available, each providing insights into how our bodies process and utilize nutrients. Let’s explore some of these critical tests.

BMR testing

Basal Metabolic Rate (BMR) is the rate at which our body burns energy while at rest. BMR testing measures the number of calories required to keep your body functioning (like breathing and circulation) without any additional activity. 

This test often involves a patient lying still under a canopy for an extended period while their oxygen consumption and carbon dioxide production are measured.

Blood tests

Blood tests can provide a snapshot of our metabolic health. Common tests include:

  • Glucose tests to check for diabetes or insulin resistance.
  • Lipid profile tests to assess cholesterol levels and overall heart health.
  • Thyroid function tests to measure how well the thyroid gland is working, given its vital role in metabolism.

Urine tests

Through urine, our body gets rid of waste products from metabolic processes. Certain metabolic disorders lead to abnormal levels of these waste products. By analyzing urine composition, doctors can identify conditions like phenylketonuria or maple syrup urine disease.

Gene testing

Genetics play a significant role in our metabolic health. Some individuals might be genetically predisposed to certain metabolic disorders. 

Gene testing helps in identifying these predispositions, allowing individuals to take proactive measures in their health and lifestyle choices.

Regular monitoring and testing are vital to catch any potential metabolic issues early on. 

Whether you’re curious about your metabolic rate or concerned about a possible genetic predisposition, these tests can offer valuable insights to guide your health decisions.

Can supplements enhance metabolism?

When considering metabolism, it’s common to hear about the potential benefits of supplements. The supplement market promises solutions to boost metabolic rate, burn fat faster, or increase energy. But do they work? And if so, how?

Understanding supplements and metabolism

Vitamin and mineral supplements

Certain vitamins and minerals play a pivotal role in energy production and metabolic processes. Magnesium, for example, is involved in over 300 enzymatic reactions in the body, many of which are related to metabolism. 

Similarly, B vitamins help convert dietary energy into ATP (adenosine triphosphate), the energy currency of our cells. 

A deficiency in these nutrients can slow down metabolic processes, so supplementing can be beneficial if there’s a confirmed deficiency.

Vitamin and mineral supplements

Green tea extract

This supplement is popularly touted for its metabolism-boosting properties. Green tea extract can elevate metabolic rate and promote fat oxidation, thanks to its catechin content.


Caffeine can temporarily raise your metabolic rate, often found in weight loss pills and pre-workout supplements. However, over time, your body may become tolerant to its effects.


This amino acid transports fatty acids into your cells to be processed for energy. While the body naturally produces it, some people take it as a supplement for better fat metabolism.


Gut health is closely linked to metabolism. Probiotics can enhance gut health, potentially aiding in better nutrient absorption and efficient energy use.

Things to consider when choosing metabolism-boosting supplements

1. Not a magic pill

While some supplements might offer a slight boost, they aren’t miracle solutions. Consistent dietary habits, regular exercise, and overall lifestyle play a more substantial role in metabolic health.

2. Safety and interactions

It’s essential to be cautious. Some supplements can interact with medications or have side effects. Always consult with a healthcare provider before starting any new supplement.

3. Quality matters

The supplement industry isn’t always tightly regulated. It’s crucial to choose high-quality, reputable brands. Researching and reading reviews can be helpful in this selection process.

4. Listen to your body

Even if a supplement is popular or works well for someone you know, it might not suit you. Pay attention to how your body responds and adjust accordingly.

Closing thoughts

Metabolism is a vital cog in the intricate machinery of our body, influencing how we use and store energy from the foods we consume. 

From the basic definition to the nuances of metabolic disorders, understanding this process can be empowering. 

It underscores the importance of a balanced diet, regular health monitoring, and proactive steps to ensure metabolic efficiency. 

By staying informed and making informed choices, we can better navigate the challenges of metabolic health and optimize our well-being for years to come.


What happens when metabolism is high?

When metabolism is high, the body burns calories at a faster rate, leading to increased energy expenditure and often resulting in weight loss if caloric intake doesn’t increase proportionally. This heightened metabolic rate can also lead to increased heat production and potentially faster processing of nutrients in the body.

Is metabolism good for weight loss?

A higher metabolism can aid in weight loss because it causes the body to burn calories more efficiently. However, for sustainable weight loss, it’s essential to combine an increased metabolic rate with a balanced diet and regular exercise.

How do I know if my metabolism is weak?

If your metabolism is weak, you may experience symptoms such as fatigue, cold sensitivity, dry skin, and unexplained weight gain. It’s essential to consult a doctor for definitive diagnosis, as they can conduct specific tests to assess metabolic health.

What drinks boost metabolism?

Green tea and black coffee have been shown to temporarily boost metabolism due to their caffeine content and other beneficial compounds. Additionally, drinking cold water can increase energy expenditure for a short time as the body works to warm it to body temperature.

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