What Is Metabolism, Anabolism And Catabolism?

Written by Andrew Brewer. ⚕️Reviewed and fact checked by our medical team.


The word metabolism is something you hear being thrown around quite a bit in the fitness and weight loss industry. Most people know its a vital part of the weight loss process, but they have no idea what it is and how it actually works. With this article we will dive in and discuss metabolism, how it works and the roll it plays in helping you lose weight. We will also discuss anabolism and catabolism and how they work in harmony with your metabolism to help you get in the best shape of your life.

Key Takeaways

  • Metabolism is a vital process that occurs within a living organism in order to maintain life. Anabolism is a process by which your body builds things up, while catabolism is the opposite as it breaks things down.
  • During the anabolic process, simple molecules such as amino acids are turned into larger, more complex molecules. This process requires a great deal of energy and is important for the growth and maintenance of tissues.
  • The key anabolic hormones include growth hormone, insulin, estrogen, testosterone, and IGF1. On the other hand, the key catabolic hormones include cortisol, adrenaline, glucagon, and cytokines.
  • Understanding how metabolism, anabolism, and catabolism work can help individuals better manage their body weight and achieve their fitness goals.
  • Lifestyle factors such as diet, exercise, and stress management can impact metabolism and the balance between anabolism and catabolism.

What is Metabolism?

According to Oxford Dictionaries, metabolism is a chemical process that occurs within a living organism in order to maintain life. These processes are needed in order for us to grow, reproduce, repair damage inside our bodies and properly respond to the environment around us.

What is Anabolism?

Anabolism is a process by which your body builds things up. During this process your body takes simple molecules such as amino acids and turns them into larger, more complex molecules. This process of course uses a great deal of energy. When your body is going through this process it allows your body to do two very important things—grow new cells and maintain all tissues. Bone growth and an increase in muscle mass are two great examples of anabolism. Without this process your body would be weak and brittle. This is why you always hear bodybuilders speaking of the importance of getting their body into an anabolic state.

During the anabolic process monomers are used to build what is known as polymers. Polymers are nothing but large complex molecules made up of several smaller molecules called monomers. Here’s a quick example of how this process works. Amino acids are made up of simple molecules or monomers. They go through a series of anabolic processes that build proteins: proteins are made up of large complex molecules, or polymers.

5 Key Anabolic Hormones

Growth Hormone – The growth hormone does exactly what its name implies. It helps you grow! It does this by stimulating the release of somatomedin. The pituitary gland is responsible for producing growth hormone.

Insulin – We all know how important insulin is. Made by the beta cells in the pancreas, this powerful hormone helps regulate blood sugar levels. Without insulin your cells would not be able to properly utilize glucose.

Estrogen – Estrogen is a female hormone that is produced, for the most part, in the ovaries. It is involved in a variety of different processes including strengthening the bones and helping females develop secondary sex characteristics, such as breasts. It also helps regulate the menstrual cycle by thickening the endometrium.

Testosterone – While estrogen is considered the female hormone, testosterone is considered to be the male hormone. Produced in the testes, testosterone is responsible for the development of key male characteristics such as  a beard and a deep voice. It is also responsible for helping men to build big, strong muscles.

IGF1 – IGF stands for insulin like growth factors. In simple terms, it is a set of hormones that assist in protein and sulfate production. Both IGF I and II play a key role in the growth and development of the uterus and placenta: they are also a vital part of the early stages of pregnancy when the fetus is just starting to grow.

What is Catabolism?

While anabolism is a process that builds things up, catabolism is the complete opposite as it breaks things down. It takes bigger, large complex molecules and breaks them down into smaller molecules all while releasing energy at the same time. Catabolism provides your body with the energy it needs for simple, everyday physical activity. It starts on a cellular level and affects every move your body makes. During the catabolic process polymers are broken down into monomers.For example, during the catabolic process amino acids that have been produced are either converted into other compounds, used to create or form new amino acids or recycled. In some cases protein is broken down into amino acids for the sole purpose of making glucose. Anytime you eat your body will break down the organic nutrients found in the food, while releasing energy. That energy is then stored in ATP molecules.

4 Key Catabolic Hormones

Cortisol Chances are you are familiar with the term cortisol. When you are under stress and anxiety, it is this hormone that kicks in and tries to protect you. The hormone is produced in the adrenal gland by the adrenal cortex. It does three very important things when you are under stress— namely reduces immune response, increases blood sugar and increases blood pressure.

Adrenalin – Whenever you are afraid you go into what is known as “fight or flight” mode.  You will either stay and fight, or you will run and seek shelter. Adrenalin plays a huge role in such scenarios.  Produced by the medulla, adrenalin is what causes your heart to beat faster. It also strengthens the force at which your heart contracts.

Glucagon – The alpha cells in the pancreas are responsible for producing this interesting hormone. It causes blood sugar levels to raise by stimulating the breakdown of glycogen in the liver. Glycogen is a carbohydrate your liver stores for future use. When you engage in physical activity, it uses the stored carbohydrates as fuel.

Cytokines – Cytokines are small proteins that have a very specific roll in how cells interact with each other. They effect communication as well as behavior.

Metabolism and Body Weight – How Does One Impact The Other?


Determining your body weight is a simple math equation, really. You take Catabolism, which is the amount of energy released into your body, minus anabolism, the amount of energy your body uses. Any energy that hasn’t been used will be stored as either glycogen or fat. When your body stores the excess energy as fat, that’s how you start to put on weight. Gaining weight, on the other hand, can be caused by eating too many calories or underlying medical issues that have gone undiagnosed. Many people believe slim individuals have a fast metabolism while overweight individuals tend to have a slow metabolism.

This, however, is not always the case. The most common cause of obesity is an under-active thyroid. And according to the UK NHS, weight gain is usually a result of an imbalance of energy. If you are considered very overweight or obese, it may be time to head to the doctors office for an evaluation. You need to find out if there is an underlying medical condition causing you to gain weight. If there are no medical issues for you to worry about, consider making a few lifestyle changes that can help you start shedding those unwanted pounds.

4 Ways To Naturally Boost Your Metabolism

While there isn’t much you can do to change your basal metabolism, which is your metabolic rate while you are at rest, there are a few strategies you can use that will have a huge impact in the long run. It’s all about determining your energy needs and changing your lifestyle to fit those needs. This is one of the best ways to experience fast weight loss.

Here are 4 strategies you can use to naturally boost your metabolism.

#1 – Figure Out Your Calorie Requirements

There is a very complicated equation you must use to determine your calorie requirements. This equation takes into account your age, gender, activity level, body composition and a variety of other factors to determine how many calories you should be eating on a daily basis. To good news is you don’t have to try and figure out your calorie requirements on your own. You can use this free calorie calculator and it will do the hard work for you; the calculator can be found at http://www.healthycalculators.com/calories-intake-requirement.php.

#2 – Reduce Your Caloric Intake

Now that you know how many calories you need to eat to lose weight, its time to make the proper adjustments to your diet. The one thing you should not do is drastically cut your calories. When you eat too few calories, your body immediately starts holding on to fat in an effort to protect you from starvation. In simple terms, instead of freely releasing fat, your body will hold on to all the energy it can find.  Another problem with a diet too low in calories is the risk of malnutrition. If you aren’t eating enough food chances are you won’t be getting the nutrients your body needs to function at optimum levels. This is not good for your health and can lead to other health issues. It can also affect your metabolism and make it even more difficult to lose weight.

You should never go on a severe calorie restricted diet unless you have been advised by a health care professional such as a nutritionist, dietitian or doctor. The sad part is the United States and the United Kingdom are the two countries with the highest rate of citizens using crash diets. Just remember if these crash diets really worked the obesity rate wouldn’t be as high as it is.

In all likelihood, avoid the crash diets and opt for a healthy well balanced diet that includes whole grains, fruits, vegetables, protein, calcium, sugars and good quality fats. Eating a well balanced diet will not only help you lose weight, but make it easier to maintain your weight as well.

#3 – Get More Exercise

Researchers at Duke University Medical Center did a six month study on the impact of exercise on those who lead a somewhat inactive lifestyle, which unfortunately, in this day and age, is the majority of people. The study involved 53 participants and focused on 17 biological facts. These biological facts have all been known to increase cardiovascular risks— and included things such as cholesterol levels, waist size, total body mass and insulin sensitivity just to name a few.

The study also measured three different levels of physical activity; these three levels were equivalent to walking 12 miles per week, jogging 12 miles per week or jogging 20 miles per week. Participants were in a supervised setting and worked out on elliptical machines, treadmills and cycle ergometers. The findings of this study were quite interesting. According to Dr Jennifer Robbins, the lead researcher in the study, intensity is not an important factory when it comes to enjoying the benefits of exercise. This, of course, is great news for those who don’t enjoy high intensity workouts. As long as you are working out in some capacity, you will be able to enjoy the many benefits of exercise. If you never worked out, we recommend you reading our how to start working out guide

Three Exercise Categories


There are three very broad categories in which exercise can be broken down into. They are aerobic exercise, anaerobic exercise and agility training.

Let’s briefly discuss each one.

Aerobic Exercise

The number one objective of aerobic exercise is to improve the way your body consumes oxygen. Aerobic exercise is usually done at a moderate pace for an extended period of time. The average aerobic exercise session would involve a warm up followed by a minimum of 20 minutes of exercise. It would then conclude with a 5 to 10 minute cool down. A great example of an aerobic exercise would be running on the treadmill for 20 minutes. Sprinting for 20 minutes on the other hand would not be considered aerobic.

Anaerobic Exercise

While aerobic exercise focuses on improve oxygen consumption, anaerobic exercise focuses on building strength, power and muscle. Anaerobic exercise consists of high intensity bouts of exercise in short 30 to 60 second bursts. Examples of anaerobic exercises include sprinting, weight lifting and any sort of interval training. By definition the word anaerobic means without air. During anaerobic exercise oxygen is not used for energy. As a result you may experience what is known as lactic acid. Lactic acid can lead to your muscles becoming fatigued and it must be used up during the recovery process. This gives your muscles a chance to refuel before you engage in another bout of intensive exercise.

Agility Training

Agility training is perfect for those looking to improve their ability to speed up, slow down and change directions while still maintaining complete control of their body. For example, in the sport of basketball agility training is extremely important as it helps the player stop on a dime and still maintain their position. Several sports including tennis, football and soccer use agility training as a way to train athletes. For best results you must do a combination of anaerobic and aerobic exercises several times a week. According to researchers at Heriot-Watt University in Edinburgh, Scotland, even short sessions of interval training can have a huge impact on how your body is able to metabolize sugar.

#3 – Get More Sleep


When it comes to losing weight and getting in shape, sleep is a key component. If you don’t get enough sleep everyday you will have trouble controlling your appetite, which can lead to overeating and your level of insulin resistance being altered. It can also increase your risk of developing Type 2 Diabetes. All of these things work together to do one thing—cause you to pack on those extra unwanted pounds.

There have been countless studies done on sleep and how a lack of it can damage your body’s ability to regulate leptin levels. Leptin is the hormone responsible for telling your body you have had enough to eat. When it isn’t functioning properly, you will continue eating even though you are full, which is, of course, is a recipe for disaster. The Integrative Cardiac Health Project at Walter Reed Army Medical Center studied the sleep patterns, activity levels and energy expenditures of 14 nurses. Each nurse wore an actigraphy armband that measured everything from body temperature, total activity level and a variety of other indices that are in some way related to activity and rest.

The participants were split into two groups so researchers could easily analyze the data. The two groups were “short sleepers” and “long sleepers”. Based on the data, short sleepers had a BMI of 28.3 while long sleepers had a BMI of 24.5. Short sleepers also had trouble getting to sleep. And once they fell asleep, they had trouble staying asleep. This study shows there is a direct link between body mass index and sleep patterns. Another study done by the University of Bristol, England found that children who don’t get enough sleep greatly increase their chances of being obese. It primarily happens due to hormones being altered because of a lack of sleep.

Studies have also shown people who get very little sleep tend to have high ghrelin levels. Ghrelin is the enzyme responsible for telling your brain you need to eat. If you have high levels of ghrelin you will end up eating way too many calories throughout the day.  One last study we will mention in this article is one done by scientists at the prestigious Columbia University in New York. The study found that when you don’t get enough sleep your glucose tolerance lowers, thereby greatly increasing your chances of gaining weight and developing Diabetes. It’s perhaps also interesting to note that those who slept too much also had an increased risk of developing diabetes.

If you are someone who has trouble getting to sleep, here are a few simple things you can do to improve your sleep patterns:

  1. Have a bedtime routine you follow

  2. Make your bedroom a relaxing space

  3. Make sure your room is dark and quite when its time to go to bed

  4. Aim for a minimum of 7 straight hours of sleep

  5. Avoid consuming a big meal right before bed

  6. Avoid intense exercise at least 4 hours before bed

  7. Keep your same bedtime schedule during the weekends


As you can see, your metabolism, anabolism and catabolism all play a major role in your overall body mass index. They all work together and play a specific roll in helping you lose weight and stay in shape. If any one of these processes is not working properly, the others can also be negatively affected.

The good news, however, is you can easily boost your metabolism by making a few key lifestyle changes. Let’s start by eating right, exercising and getting at least 7 hours of sleep every night. When you follow this practice to a tee, you will immediately start to notice a marked difference in how you feel. Keep in mind that it’s not about making big changes. Start small and work your way up. For example, if you haven’t worked out in 5 years, don’t start by going to the gym 5 days a week. Start out with just 3 workouts a week. Limit each session to 45 minutes to an hour. As you get stronger you can work your way up and increase your workout times as well as the intensity of your workouts.

You should take the same approach with your diet. Don’t try to cut everything out cold turkey. Take it one step at a time. For instance, if you normally drink 3 sodas a day, take it down to 2 for a period of two weeks. After that you can cut it down to one for another two weeks. Before you know it you will be drinking less than 3 sodas a week. That means you will be saving yourself well over 1000 calories per week and it will quickly start to show in the mirror. Another important tip as far as diet goes is to start preparing your meals in advance. Eating healthy is not always easy as it will require you to prepare more of your meals at home.

That’s why preparing your meals in advance is so important. Who wouldn’t like something healthy handy when its time to eat? You can literally just grab it and go. When you take the gradual approach you greatly improve your chances of success. And while it won’t be easy, it will be well worth it in the long run. Especially when you start to see those extra pounds disappear.


  • What is metabolism?

Metabolism refers to all the chemical reactions in an organism to maintain life, including the breakdown of molecules to obtain energy (catabolism) and the synthesis of molecules for growth and repair (anabolism).

  • What is anabolism?

Anabolism is the set of metabolic pathways that build complex molecules from simpler ones, using energy in the process. Examples include the synthesis of proteins from amino acids or glycogen from glucose.

  • What is catabolism?

Catabolism is the set of metabolic pathways that break down complex molecules into simpler ones, releasing energy. Examples include the breakdown of glucose into pyruvate in glycolysis or the breakdown of fats into fatty acids and glycerol in lipolysis.

  • How do anabolism and catabolism work together in metabolism?

Anabolism and catabolism work together to maintain the body’s molecules and energy balance. Catabolism provides energy and building blocks for anabolism, while anabolism uses energy to synthesize molecules for growth and repair. Together, they regulate the metabolism of an organism.

  • What factors can affect metabolism?

Metabolism can be affected by various factors such as age, sex, genetics, body composition, hormones, diet, exercise, and environmental factors.

  • Can metabolism be changed?

Yes, metabolism can be changed through lifestyle modifications such as increasing physical activity, reducing calorie intake, and maintaining a healthy diet. However, genetic factors also play a role in determining a person’s metabolic rate.

  • Is it possible to increase metabolism to lose weight?

While metabolism plays a role in weight loss, increasing metabolism alone cannot guarantee weight loss. A combination of a healthy diet, regular exercise, and lifestyle modifications may help promote weight loss by increasing metabolism and energy expenditure.

  • What are some disorders related to metabolism?

Some disorders related to metabolism include diabetes, phenylketonuria (PKU), hypothyroidism, and hyperthyroidism, among others. These conditions involve abnormal metabolic processes that can have significant health consequences.

Andrew Brewer

Andrew Brewer

Andrew Brewer started Fastingapps.com to give people the guidance that he never received when he was first starting. His goal is to make your goals achievable and to offer you only the best fasting apps that the internet has to offer. You're not on your own - Andrew and the entire family of reviewers at Fastingapps.com are here with you every step of the way!