Metabolically speaking

Good morning.

This week I want to provide some clarity on all things metabolism. 

It’s a poorly understood subject, due to a combination of bad explanations and devious claims when it comes to moving products.

The metabolic misunderstanding comes from the confusion of three key terms, which I’ll define here:

  • Metabolism: chemical reactions in the body; the energy expended from these reactions can be measured
  • Basal Metabolism: energy expenditure required to sustain life - ie. the component of metabolism that is essential for life; a component of Total Energy Expenditure
  • Total Energy Expenditure: the amount of energy used by the body; often used interchangeably with metabolism


Your metabolism is the sum of all the reactions that occur in your body. It is the same number as your Total Energy Expenditure.

However, Basal Metabolism is only one component of Total Energy Expenditure/Metabolism, so these terms cannot be used interchangeably.

There are four component of Total Energy Expenditure

  • Basal metabolism (energy required to maintain life - ie. lying in bed without movement)
  • Exercise activity thermogenesis (energy required during exercise)
  • Non-exercise activity thermogenesis (energy required for movement - ie. sitting, typing, etc)
  • Thermic effect of food (energy required to break down food)


I will cover each of these over the rest of the week. But for now, I just want to focus on three terms. 

A misunderstanding of these terms is what causes confusion with energy expenditure. These are three differing terms that are closely related and easily confused.

Keep this in mind for tomorrow’s email.

Tom Fitzgerald