Anabolic vs Catabolic States: Metabolism Explained In Detail

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Understanding how your metabolism works can be difficult if you have not spent much time learning about biochemistry and physiology since you were in school. 

However, while the nitty-gritty details of fully understanding how your body’s metabolism works can be highly complex, familiarizing yourself with just the basics of anabolic vs catabolic states can be extremely helpful for understanding how your body works and how to adjust your diet and exercise to meet your physique goals.

But, what is an anabolic state? What is a catabolic state? Is it better to be in a catabolic vs anabolic state? What is the difference between catabolism vs anabolism?

In this article, we will discuss the basics of muscle metabolism, helping to differentiate an anabolic vs catabolic state and what induces a catabolic state or anabolic state.

More specifically, we will cover the following: 

  • What Is Metabolism?
  • What Is an Anabolic Vs Catabolic State?
  • Is Exercise Anabolic or Catabolic?

Let’s dive in! 

Blocks that spell out metabolism which includes anabolic vs catabolic states in the body.

What Is Metabolism?

Before we delve into the specifics of differentiating a catabolic vs anabolic state, let’s take a few steps back and discuss what an anabolic state refers to, what a catabolic state refers to, and the basics of metabolism in general.

We often think of metabolism as being fast or slow and something that just determines whether we are losing or gaining weight.

Although it is true that your metabolism has a significant impact on changes in your weight, our typical idea of metabolism in common parlance is a very simplified version of a much more complicated term.

Metabolism refers to the sum total of the biochemical reactions in your body.

Thus, your metabolism includes a set of anabolic processes and catabolic processes that actually occur simultaneously in order to help sustain your life, repair and regenerate cells and tissues, digest and absorb nutrients, and produce energy for your workouts and everyday activities.

A person getting ready to run.

Therefore, your metabolism helps provide and release energy to the body.

Metabolism is largely governed by hormones.

Anabolic processes and catabolic processes are generally associated with distinct sets of hormones.

Anabolism primarily involves testosterone, estrogen, growth hormone, and insulin.

On the other hand, hormones associated with catabolism include cortisol, epinephrine, glucagon, and cytokines.

Thyroid conditions, PCOS, diabetes, or other disorders that affect your hormones can thus affect your overall metabolism.

What Is an Anabolic Vs Catabolic State?

Within the overarching umbrella of metabolism, there are catabolic processes and anabolic processes.

Whether you are in a catabolic vs anabolic state or an anabolic vs catabolic state has to do with the overall bias when looking at your metabolism. 

Generally, people who are looking to alter their physique, either by losing fat or building muscle, are mostly interested in whether their muscle metabolism is favoring an anabolic vs catabolic state or catabolic vs anabolic state.

In other words, both anabolic and catabolic processes will be occurring simultaneously, but if more catabolism is occurring than anabolism, you are in a catabolic state, and if the anabolic processes of foods are outpacing the catabolic processes, you are in an overall anabolic state.

A person drinking a bottle of water.

Anabolism

So, what is anabolism or an anabolic process?

Anabolism, or anabolic process, is one in which smaller molecules are assembled together into larger molecules. In this way, an anabolic state or anabolism leads to tissue growth, building muscle, or assembling larger biomolecules in your body.

An example of an anabolic process is forming muscle and liver glycogen from glucose molecules released in the bloodstream.

The glucose molecules are assembled together into larger glycogen molecules, which then serve as the storage form of carbohydrates in the body.

Muscle anabolism leads to muscle growth or hypertrophy.

People on exercise bikes.

Catabolism

Catabolism is the opposite of anabolism.

A catabolic process breaks down larger molecules into their constituent parts. A catabolic process may help release energy or provide nutrients.

For example, digesting food that you have consumed is a catabolic process. The macronutrients (carbohydrates, proteins, and fats) are broken down into their building blocks so that the nutrients can be absorbed and used by the body.

Large carbohydrate molecules, termed polysaccharides, are broken down into simple sugars like glucose that can then enter the bloodstream and be taken up by cells to produce energy.

Proteins are broken down to amino acids by breaking the peptide bonds. Fats are broken down into glycerol molecules and free fatty acids.

Another example of a catabolic process is glycolysis. Glycolysis is an energy-generating pathway that takes place in the cytosol of your cells, breaking down a molecule of glucose into smaller molecules (pyruvate or lactate) along with ATP, which is usable cellular energy.

Muscle catabolism refers to the breaking down of muscle tissue.

A person walking on a treadmill.

Is Exercise Anabolic or Catabolic?

A strenuous workout will induce muscle catabolism, because even though carbohydrates and fats are the primary sources of fuel for the muscle cells to generate the ATP or energy necessary to support exercise, some amount of protein is also broken down.

The only form of protein storage in the body is muscle tissue. Therefore, when you break down protein during a workout, you are undergoing muscle catabolism.

In most cases, protein provides less than 10% of the total calories you need during your workout.

However, as the intensity and duration of your workout increase, the contribution of protein to help provide usable ATP to sustain your exercise may increase upwards of 15% or so, depending on your nutritional status and the intensity and duration of the workout.

For example, there will be more muscle catabolism during a long run for marathon training than for a short, easy run.

Muscle catabolism can also occur after a vigorous workout, particularly a heavy or intense strength training workout.

Kettlebell push ups.

Muscle fibers get damaged when they are overloaded with heavy resistance and higher volume training.

If you are in a healthy balance between the catabolic vs anabolic processes, this muscle damage will then be repaired via anabolic processes.

Muscle protein synthesis is an anabolic process that involves assembling new reparative proteins from available amino acid building blocks. These reparative proteins are shuttled to the sites of muscle damage, where they can then be inserted along areas of muscle fibers that have been damaged.

In doing so, the anabolic process of muscle protein synthesis helps strengthen and build your muscle fibers, resulting in overall gains in muscle size and strength. 

This is because the muscle fibers have become thicker and thus both more resilient and able to produce more force as well as larger in overall size.

As mentioned, as long as you are in a healthy, balanced metabolic state, your muscles should be repaired after a workout. 

A back squat.

However, if you are in an overall catabolic state, you will experience more muscle catabolism both during exercise as well as at rest.

So, how does this occur? What causes a catabolic state in the body?

First of all, it’s important to reiterate that there are always anabolic and catabolic processes occurring simultaneously in the body.

Whether you are in a catabolic vs anabolic state or an anabolic vs catabolic state can change throughout the time course of the day.

For example, after you eat a meal or snack, your body is flooded with “resources“ to be used for energy.

Although catabolism must first occur to harness the nutrients and energy in the food that you eat, you will be in an overall anabolic state shortly afterward because the body now has a bounty of energy to build larger molecules, cells, and tissues and engage in reparative or growth processes.

When you haven’t eaten in a while, or after a lot of energy is used for a vigorous workout, you are in a catabolic state until you refuel and provide your body with more nutrients.

A single arm kettlebell swing.

Intense exercise training, a calorie-deficient or low-fat diet, or a combination of both (as seen in relative energy deficiency in sport (RED-S)), can impact hormone production and the resultant anabolic vs catabolic state.

For example, one study that investigated the hormonal anabolic vs catabolic balance of bodybuilders training for a competition Looked at the impact of diet and caloric intake on muscle metabolism and hormonal balance.

Some of the male bodybuilders trained and consumed their normal diet while others were put on a calorie-restricted diet to try to reduce body fat. This can be thought of as a “cutting” diet.

The bodybuilders who were on the cutting diet lost a significant amount of both body fat and lean body mass or muscle tissue relative to the bodybuilders following a diet with a sufficient number of calories.

Moreover, bodybuilders who were restricting calories had significantly lower levels of insulin, testosterone, and growth hormone, particularly as the weeks went on with continued caloric restriction.

These results suggest that the anabolic pathways and anabolic hormones were compromised by cutting calories and failing to meet energy needs.

Particularly when testosterone and growth hormone levels are low, muscle growth and repair are compromised, as well as general healthy cell turnover, tissue repair, and energy levels.

A woman doing a dumbbell row.

Additionally, when you are in a catabolic state, it is much more difficult to maintain muscle mass, and body fat percentage may increase. 

Adipose tissue, which is stored body fat, is less metabolically active than muscle tissue. Therefore, if your caloric intake is insufficient for an extended period of time, muscle tissue will be metabolized for energy and this will increase your relative body fat percentage. 

Moreover, because your metabolism slows down when you are not consuming enough calories in order to help conserve energy and make better use of the calories that are coming in, body fat storage can increase with even a small surplus of calories.

Therefore, while bodybuilders looking to cut weight and lose body fat do want to have some amount of catabolism going on in order to lose fat, nutritional strategies should be employed to prevent muscle catabolism and the relative paucity of anabolic hormones.

Evidence suggests that the most effective diet for building muscle in a caloric deficit is to consume 2.3-3.1 g/kg of lean body mass per day of protein, 15-30% of your total calories from fat, and the remainder from carbohydrates. 

Furthermore, research suggests that you should not try to lose more than 0.7% of body fat per week. So, for example, if you weigh 75 kg, this works out to 75 x 0.007 = 0.525 kg or 1.2 pounds of fat loss per week.

To learn more about how to build muscle, check out our guide to supporting muscle growth here.

A muscular man lifting a barbell.
Photo of author
Amber Sayer is a Fitness, Nutrition, and Wellness Writer and Editor, as well as a NASM-Certified Nutrition Coach and UESCA-certified running, endurance nutrition, and triathlon coach. She holds two Masters Degrees—one in Exercise Science and one in Prosthetics and Orthotics. As a Certified Personal Trainer and running coach for 12 years, Amber enjoys staying active and helping others do so as well. In her free time, she likes running, cycling, cooking, and tackling any type of puzzle.

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