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Metabolism 101

People often think of “metabolism” as the ability to burn calories and manage weight. Metabolism, however, is so much more than that.


The term “metabolism” refers to all of the chemical reactions that take place throughout the body, which power all bodily functions and keep us alive. Too vague? We’ll give you the rundown:

We consume food composed of protein, carbohydrates, and fat
That food is broken down during digestion into things like amino acids (from protein), simple sugars (from carbs), glycerol, and fatty acids (from lipids)
These compounds are then absorbed into the blood and transported to the cells, where they can be used for one of two types of metabolic activities:

  • Anabolism (or constructive metabolism): these smaller compounds are used as building blocks to make larger cellular structures. Anabolism helps us grow new cells, repair tissue, and store energy.
  • Catabolism (or destructive metabolism): these compounds are broken down to release energy and power all bodily functions. Catabolism powers anabolism, heats our bodies and allows our muscles to move.


On a daily basis, our bodies expend energy for 3 main purposes: resting energy expenditure, diet-induced thermogenesis and physical activity expenditure.

  • Resting energy expenditure is the minimum energy that we need to exist and maintain basic bodily functions. Also called basal metabolic rate (BMR), this makes up for 60-70% of our total energy expenditure on a given day.
  • Diet-induced thermogenesis (or dietary induced energy expenditure) is the amount of energy required to digest, absorb and store the food that we eat. This makes up for about 5-10% of the energy we expend on a daily basis.
  • Physical activity energy expenditure is the energy that we use to move around (for both exercise and non-exercise activities). This is the most variable, and can account for 20-40% of the energy we expend during a given day.


“Metabolic health” is a confusing and often misused term. Generally, being “metabolically healthy” means that a person has ideal levels of blood sugar, cholesterol, blood pressure, and a healthy body composition (sometimes evaluated as waist circumference).

More simply, being metabolically healthy means that your body can effectively produce energy to power bodily functions.

Metabolism vs. Metabolic Health
The term “metabolism” refers to all of the chemical reactions that take place in the body, which help us create the energy we need to function. “Metabolic health” is a measure of how effectively our body produces this energy.


Just like different things can affect your resting heart rate or blood pressure, a number of different factors can influence your metabolic health. Studies have shown that genetics can have a significant impact on how much energy we expend on a daily basis. Diet also has a measurable impact on energy expenditure. A protein-heavy diet, for example, increases your daily energy expenditure, because protein requires more energy to digest than carbs or fats. Activity, muscle mass, and hormones can also impact your metabolism.


Whether you are an older individual or simply concerned about metabolic health, there are a number of lifestyle changes you can make to benefit your metabolism.

  • Try adding more protein to your diet, particularly if your intake is low
  • Exercise (especially resistance training, or HIIT workouts)
  • Enter ketosis (try intermittent fasting, a keto diet or Metabolic Switch®)
  • Get enough sleep (poor sleep has been linked to obesity)

While we all know someone who seems to have a “magic” metabolism, there are many things we can do to support metabolic health. So, if you’re worried about metabolic health, now’s the time to get started.