Fuel metabolism and the ketogenic diet

Under ‘normal’ dietary conditions, the body runs on a mix of carbohydrates, protein and fat.
When carbohydrates are removed from the diet, the body’s small stores are quickly depleted.
Consequently, the body is forced to find an alternative fuel to provide energy. One of these fuels is
free fatty acids (FFA), which can be used by most tissues in the body. However, not all organs
can use FFA. For example, the brain and nervous system are unable to use FFA for fuel ;
however, they can use ketone bodies.

Ketone bodies are a by-product of the incomplete breakdown of FFA in the liver. They
serve as a non-carbohydrate, fat-derived fuel for tissues such as the brain. When ketone bodies
are produced at accelerated rates, they accumulate in the bloodstream, causing a metabolic
state called ketosis to develop. Simultaneously, there is a decrease in glucose utilization and
production. Along with this, there is a decrease in the breakdown of protein to be used for energy,
referred to as ‘protein sparing’. Many individuals are drawn to ketogenic diets in an attempt to
lose bodyfat while sparing the loss of lean body mass.

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