Physiology Of Low Calorie Dieting

The human body needs a minimum of around 800kcal daily simply to have sufficient energy to ‘power’ its vital organs. Eating fewer than 1,200kcal daily starts the rapid conversion of first, our available blood sugar and then, as this dwindles, our stored glycogen reserves into instantly usable ‘energy’.

However when we consume less than 800kcal daily, we begin involuntarily converting very heavy glycogen reserve into an energy form which the body uses to maintain the brain, nervous system, liver, kidney and other vital functions.

This state is known as ‘being in ketosis’. Ketosis occurs when glycogen is converted into fatty acids and ketones both of which are then used as our alternate essential energy source when blood sugar (glucose) falls below minimum levels. 

Ketosis begins within the first 3-4 days of very low calorie dieting and starts even more acutely when undertaking total food replacement. 

Put simply, when our intake falls below 800kcal daily our critical needs are met by burning up very heavy glycogen reserves. The fewer unnecessary kcal we eat the more heavy glycogen is converted - so reducing our weight, swiftly!