What Is Metabolism? Process, Biology and How It Affects Your Body

October 10, 2024

When discussing health, weight, and nutrition, you may hear experts mention metabolism. It can be fast or slow, but what is metabolism, and what does it mean?

 

Age, body composition, hormone functions, degree of physical activity, nutrition, and other factors, can impact metabolism. Understanding metabolism is essential for enhancing not just our weight but also our general health and wellbeing.

 

What does metabolism mean? Read on to learn what it is and how it can affect you.

Table of Contents

  • What is metabolism?
  • How does metabolism work?
  • What factors affect metabolism?
  • What hormones influence metabolism?
  • What is metabolism in biology?
  • Metabolism and weight loss
  • Benefits of a healthy metabolism
  • Natural ways for sustaining a healthy metabolism
  • Metabolism FAQs
  • Summary of what is metabolism

What Is Metabolism?

Many of us have just a vague understanding of what metabolism is. Generally, we consider metabolism to be a single process. However, it is the sum of all energy-producing and energy-consuming processes that take place within our bodies, such as:

  • Digestion.
  • Circulation of blood.
  • Regulation of body heat.
  • Cell growth and repair.
  • Maintaining hormonal balance.

 

When you eat an apple, for example, your digestive system breaks it down into compounds such as carbohydrates, lipids, amino acids, vitamins, minerals, and phytonutrients. The molecules enter the bloodstream after being absorbed by the intestines and are dispersed to cells. While some of these chemicals assist cellular functions, others are used to produce energy. That is metabolism.

How Does Metabolism Work?

Following a meal, the metabolic process breaks down the food’s calories and integrates them with oxygen to release the energy the body requires to function.

 

Even when you’re at rest or sleeping, your body works in various ways. Your lungs continue to take in and release oxygen, your heart keeps pumping blood, and your cells keep repairing and growing. Energy, delivered to the body through the foods we eat, is needed for each process.

Metabolic Pathways

Bioenergetics is a term that refers to the biochemical or metabolic routes that a cell uses to obtain energy. Energy is an essential element of metabolism.

 

Two processes make up the overall metabolic cycle. Both are essential for the cell’s energy balance to be maintained:

  • Anabolism – the process by which the body generates new cells, maintains tissues, and stores energy.
  • Catabolism – the process through which macromolecules, such as proteins, sugars, or fatty acids are broken down to produce energy.

What Factors Affect Metabolism?

Some people’s metabolism is faster than others. A range of factors influences how metabolism differs from one person to another. The following are some of the factors that may affect the way that your metabolism works:

metabolism factors

  • Age: People typically develop adipose tissue and lose muscle mass as they age, which results in a 1% to 3% per decade drop in basal metabolic rate [1] [2].
  • Sex: Testosterone plays a key role in carbohydrate, fat, and protein metabolism. Because men naturally have higher testosterone levels in their systems than women, less body fat, and more muscle, they typically have a higher metabolism [3].
  • Body composition: Muscle burns more calories than fat. For example, an individual with 75 pounds of muscle mass and 40% body fat burns fewer calories at rest than one with 110 pounds of muscle mass and 30% body fat [4].
  • Physical activity: Exercise builds muscle mass and revs up your metabolic engines, which burn calories quicker even when at rest.
  • Diet: Certain foods can either increase or decrease metabolism. For example, protein-rich foods, spicy peppers, and leafy green vegetables can boost metabolism. Fasting or crash dieting causes lean muscle mass loss and a slowed metabolism.
  • Hormonal factors: Hormonal imbalances might also have an impact on metabolism. For instance, the thyroid gland regulates numerous metabolic pathways involved in the breakdown and synthesis of carbohydrates, lipids, and proteins. When your thyroid gland produces insufficient hormones, your metabolism slows [5].

What Hormones Influence Metabolism?

Hormones are small molecules made by the endocrine system that act as chemical messages in the body. They regulate nearly all the processes in the body, including metabolism. 

 

Regardless of age or gender, testosterone and estrogen hormones regulate vital metabolism functions such as food intake, body weight, and body fat distribution [6] [7]. Other critical hormones in maintaining a healthy metabolism include insulin, cortisol, leptin, ghrelin, triiodothyronine (T3), and thyroxine (T4).

What Is Metabolism in Biology?

In biology, metabolism is defined as the set of life-sustaining chemical processes. These allow all living organisms to convert the chemical energy stored in molecules into usable energy for cellular functions.

 

Animals get their energy from food, and their metabolism breaks down the proteins, lipids, and nucleic acids to provide chemical energy for these functions. Plants transform the solar energy in light into chemical energy that is stored in molecules through the process of photosynthesis.

Metabolism and Weight Loss

Is there a clear link between metabolism and weight loss? The short answer is yes. Boosting metabolism is the holy grail of all dieters, but how rapidly your body burns fat depends on various factors. 

 

While you cannot change your age, gender, or genetics, you can boost your metabolism through multiple methods. Some ways to boost your metabolism include exercise, not skipping meals and even getting a good night’s rest.

How Does Metabolism Affect Weight?

Whether your metabolism is rapid or slow, your body is designed to store surplus energy in fat cells. Therefore, if you take in more calories than you burn daily, excess calories are stored as body fat.

 

In contrast, you will lose weight if you consume fewer calories than you expend via daily activities, such as exercise, rest, and sleep. Additionally, our metabolism slows during starvation, resulting in decreased calorie expenditure. That’s one reason why losing weight is difficult.

What Is the Basal Metabolic Rate?

The basal metabolic rate (BMR) is the number of calories needed to sustain essential living activities such as breathing, circulation, and cell formation. This amount accounts for approximately 60% of your total calories expended daily. 

 

Rapid weight reduction and extreme calorie restriction decrease your BMR; this is one of the reasons why weight loss is typically not linear and reaches a weight loss plateau at some time.

 

Your BMR can be estimated considering your height, weight, age, and gender, and it will show you how many calories your body needs to function. Once you’ve determined your BMR, you can calculate your total metabolic rate. This figure is the sum of your BMR and the calories burned through physical activity.

 

Using a fitness tracker is the most straightforward approach to calculating the total number of calories burned while exercising. For instance, if your basal metabolic rate is 1200 and you burn 700 calories per day through exercise, your metabolic rate is approximately 1900 calories.

What Is the Resting Metabolic Rate?

Resting metabolic rate (RMR) measures the number of calories burned while asleep or resting. RMR is essential for maintaining fundamental neurological functioning in addition to respiration, organ function, and blood circulation. 

 

Knowing your RMR is vital because your body will store any calories consumed in excess as fat. Being largely determined by your total lean mass, RMR decreases by about 0.01 kcal/min for each 1% increase in body fat.

Differences Between BMR and RMR

BMR and RMR are methods of calculating the calories required for your body to maintain healthy homeostasis. RMR is the energy you use while at rest or when inactive. 

 

The energy your body uses for vital processes, including breathing, blood circulation, and organ function, is measured more accurately by BMR. The differences in the final measurements impact the final result, resulting in differences between the rates.

How To Determine Your Metabolic Type?

Metabolic testing is one of the most effective approaches to obtaining an in-depth understanding of one’s metabolism.

 

There are multiple types of metabolic testing, and each gives a unique set of results:

  • Lactate threshold (LT) testing can assess the optimal training intensity and track the progression of athletes of various levels.
  • Resting metabolic rate testing estimates the number of calories burned during a normal resting or non-exercising state. This figure is essential for developing a weight loss, weight gain, or weight maintenance plan.
  • VO2 max testing determines the maximum amount of oxygen utilized during physical activity. It provides information about aerobic or cardiovascular fitness and metrics of efficiency.

Benefits of a Healthy Metabolism

Maintaining a healthy metabolism lowers your risk of developing illnesses such as cardiovascular disease, stroke, type 2 diabetes, obesity, renal disease, and nonalcoholic fatty liver disease [8]. 

 

This means that your body can assimilate the nutrients from the food you eat without experiencing harmful surges in blood sugar, blood lipids, or insulin.

Natural Ways To Maintain a Healthy Metabolism

Although certain factors affecting your metabolism are beyond your control, there are some strategies to support your metabolism:

maintain healthy metabolism

  • Consume enough protein – Protein helps stabilize insulin secretion into our bloodstream, which can boost metabolism. Protein-rich foods like eggs, fish, chicken, tofu, nuts, beans, and lower-fat dairy products, may also make you feel full faster, helping you eat less.
  • Eat spicy foods – Capsaicin, an active component of chili peppers, has been demonstrated to improve metabolism. Consuming spicy meals containing this chemical triggers the body’s fight-or-flight response, temporarily boosting metabolism [9].
  • Drink green tea – The catechin epigallocatechin-3-gallate (EGCG) found in green tea can enhance fat metabolism at rest and during exercise [10].
  • Get regular exercise – Regular aerobic exercise, strength training, and high-intensity interval training enhance metabolic function by improving fat-burning for hours following a session. The body uses more energy than fat to sustain muscle mass, which has a lower metabolic rate than muscle. More muscle mass means a higher resting energy expenditure (calories burned) and basal metabolic rate (BMR).

What Is Metabolism? FAQs

Let’s answer some commonly asked questions about metabolism.

Can I Improve My Metabolic Health?

Yes. Although factors outside your control, like genetics and age, impact you, some dietary and lifestyle changes can help you increase your metabolism. Taking a supplement may also give your metabolism a boost. When comparing the top supplements like PhenQ vs Phen24, both contain ingredients which have shown promising results in short-term treatment of obesity.

Does Metabolism Slow Down With Age?

Metabolism slows down with aging. According to studies, our metabolic rate begins to slow down by 1% to 3% per decade starting in our 20s.

What Happens When Your Metabolism Is Slow?

Slow metabolism leads to low energy expenditure. The result is an excess of energy (calories). The surplus energy is turned into fat and stored in the body, resulting in weight gain.

 

A low resting metabolic rate can lead to cardiovascular disease, diabetes, stroke, and other health problems. Maintaining a healthy metabolic rate is, therefore, essential.

What Foods Can Help You Boost Your Metabolism?

Seeds, nuts, vegetables, fruits, legumes, beans, peas, lentils, whole grains, and healthy fats, like olive oil, can enhance your metabolism. 

 

A high-protein diet can also speed up the body’s metabolic rate due to the increased energy required for protein digestion and processing.

 

Adding a simple supplement to your diet, such as keto gummies, may also help boost your metabolism.

Summary of What Is Metabolism

So, what is metabolism?

 

Metabolism is a whole caboodle of chemical processes that support life inside cells and organs. This includes changing food into energy, building vital molecules like proteins and nucleic acids (DNA, RNA), and eliminating metabolic waste. Whether active or asleep, your metabolism gives your body the energy to function efficiently.

 

Depending on several factors, including age, body size, activity level, gender, and overall health, metabolism can speed up or slow down. Nonetheless, a well-balanced diet and regular exercise can optimize your metabolism.

 

References

  1. H. Shimokata and F. Kuzuya. “Aging, Basal Metabolic Rate, and Nutrition.” Nihon Ronen Igakkai Zasshi. Japanese Journal of Geriatrics, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/8361073/
  2. Leonard S. Piers et al. “Is There Evidence for an Age-Related Reduction in Metabolic Rate?” Journal of Applied Physiology, 1 Dec. 1998, https://journals.physiology.org/doi/full/10.1152/jappl.1998.85.6.2196
  3. Daniel M. Kelly and T. Hugh Jones. “Testosterone: A Metabolic Hormone in Health and Disease.” Joe, BioScientifica, 1 June 2013, https://joe.bioscientifica.com/view/journals/joe/217/3/R25.xml#:~:text=Abstract-,Testosterone
  4. ZiMian Wang et al. “Evaluation of Specific Metabolic Rates of Major Organs and Tissues: Comparison Between Nonobese and Obese Women.” Wiley Online Library. https://onlinelibrary.wiley.com/doi/full/10.1038/oby.2007.256
  5. Rashmi Mullur et al. “Thyroid Hormone Regulation of Metabolism.” Physiological Reviews, 1 Apr. 2014. https://journals.physiology.org/doi/full/10.1152/physrev.00030.2013
  6. Deborah J. Clegg “Minireview: The Year in Review of Estrogen Regulation of Metabolism.” OUP Academic, Oxford University Press, 1 Dec. 2012. https://academic.oup.com/mend/article/26/12/1957/2614784
  7. Traish Abdulmaged. “Testosterone and Weight Loss”. Current Opinion in Endocrinology, Diabetes, and Obesity.

https://journals.lww.com/co-endocrinology/Fulltext/2014/10000/Testosterone_and_weight_loss__the_evidence.2.aspx

  1. Silvio Buscemi et al. “A Low Resting Metabolic Rate Is Associated with Metabolic Syndrome.” Clinical Nutrition (Edinburgh, Scotland), U.S. National Library of Medicine. https://pubmed.ncbi.nlm.nih.gov/17936441/
  2. James Rogers et al. “Capsaicinoids Supplementation Decreases Percent Body Fat and Fat Mass: Adjustment Using Covariates in a Post Hoc Analysis.” BMC Obesity, BioMed Central, 13 Aug. 2018, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6088424/
  3. Adrian B. Hodgson et al. “The Effect of Green Tea Extract on Fat Oxidation at Rest and during Exercise: Evidence of Efficacy and Proposed Mechanisms.” Advances in Nutrition (Bethesda, Md.), American Society for Nutrition, 1 Mar. 2013, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3649093/