During an extended low-calorie diet (near fasting, the body increases the utilization of as a source of energy?

Body fat is used when extended low-calorie diet is used. This creates a state in which consumption of energy is lower than the intake of energy, which forces the body to use the body fats to be used for the production of energy. Not only body proteins, but body proteins are also started to be metabolized for energy production. This decreases body weight.