Yes, we are most definitely (and quite refreshingly) unique. In fact, this individuality extends deep into our anatomy and physiology. This includes the chemical processes that happen deep within our cells, and your metabolism, that inner furnace, is a prime example.

A study by Gary Lewis, MD, Robert Gerszten, MD from Massachusetts General Hospital demonstrated just how individual our metabolisms can be. They reported that the small molecules in our blood, known as metabolites or end-products from energy metabolism, can tell us whether the person is burning mainly sugar (glucose), fat or protein (glucogenic amino acids) for energy.

This is known as metabolomics and it’s used to help us understand and categorise chemicals in our body so that we can understand what’s happening. In this case we are looking at the fuels we are using and when.

Your ‘Metabolic Signature’

Your metabolism could theoretically identify you based on your predisposition to breakdown certain fuels for energy. Basically, if you are the fittest person in a room of 5 decidedly unfit people then your metabolic signature would be the one that burns the most fat as a fuel source.

The researchers took 25 of some of the fittest people around immediately after completing a marathon and found they were able to metabolise fat for energy literally 1000x more effectively than less fit runners (those with significantly slower race times). Furthermore, contrary to what you might expect, the runners that ran fastest and logically put their bodies under the most strain actually presented with less damaging metabolites (waste products) in their blood.

Afterburner effect

In addition to the greater fat metabolism during the race, the elevated efficiency at burning fat for energy continued for up to an hour post-race! This pattern was also evident in the less fit individuals too.

On the flip side of this equation, the more sedentary you are i.e. the desk workers, bus, lorry or delivery drivers among us (for example) the greater your ability to store fat becomes. They say money goes to money, well I’m afraid fat goes to fat too guys.


Lewis, G. and Gerszten, R. (2012). The Exercise Effect. Massachusetts General Hospital.

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