Fasting is an act or ritual which has multiple benefits whether it is for weight loss or the ritual itself.
Fasting, as a ritual, is refraining from drinking and eating for a specific period of time.
Fasting for 16 hours a day puts deep effect on body; it helps in:
Increasing insulin sensitivity
Strengthening immune system
Our body passes through several stages while fasting and fulfills the requirements of body needs whenever blood glucose level drops.
Primary and highly efficient energy source for body is carbohydrate, that is, Glucose. Initially, glucose level in blood is pretty high and it is either used by the body or stored in the form of glycogen in muscles.
It is the quickest and best fuel for body as it provides energy to brain quite rapidly. Glycogen is also a carbohydrate which breaks down into glucose when there is need of glucose in a tissue and through bloodstream, glucose flows to the working tissue.
Glycogen breakdown occurs in the absence of insulin in blood but in the presence of glucagon. The glucose and glycogen sources present in liver may last approximately for 8 hours without high muscular activity; after this, body moves to other energy reserves.
Fat tissue is also called adipose tissue and fat cells are specifically produced as energy reservoirs when carbohydrate sources in body deplete.
Our greater intelligence, hypothalamus, looks for alternative energy sources which are fat reserves in adipose tissues.
At this stage, insulin surge is already diminished. Body undergoes a stress situation to cope with the energy needed to survive, then the stress hormones (adrenaline hormones) jump in. Adrenaline hormones are basically two hormones epinephrine and norepinephrine, which work to stimulate the catabolism of triacylglycerols (fats) into its respective components, fatty acids and glycerol. This process is called ketosis, which is the metabolism of fats.
Glycerol, then, converts into carbohydrates mainly glucose and ketone bodies. This completes the demand of body by providing sufficient energy.
The byproduct of ketosis is ketone bodies which are the source of energy for brain, especially, during the times of fasting.
People use Ketosis procedure for weight loss and for getting free of water weight. This process is also called gluconeogenesis.
Apparently and deductively, obese people may survive drought or fasting for a longer period of time as compared to thin and smart people due to the fat around their waists and the fat present within their muscle cells.
When blood glucose level drops, it moves to another reliance of the body, which is muscle protein and we are compelled to catabolize protein.
Breakdown of protein into amino acids provides energy for ATP production. This process is called proteolysis and the breakdown of body protein into its constituent parts for energy supply when glucose level drowns is called gluconeogenesis.
Protein catabolism takes longer time than fats and large carbohydrates. That is why it is a slow energy source as compared to the others.
It is to be noted that the extent of usage of an energy source can not be described precisely because every person differs in his/her hormonal levels and metabolism.
Some may also have psychotic disorders like bulimia nervosa, which may not allow them to fast; such people’s bodies have capability to survive the fasting condition but their minds are afraid to do so.