Intermittent fasting IF is a recurring dietary pattern in which individuals consume little to no calories for a prolonged period of time, such as 16 to 48 hours, followed by periods of normal energy intake.
Time-restricted feeding TRF is also a type of IF; it is characterized by a restriction in caloric intake for 8 hours or fewer each day. These different modes of fasting are used as an approach to enhance physical and mental performance based on the theory that mammals have optimally adapted to periods of fasting or starvation.
IF has been shown to decrease body fat while allowing for the retention of lean body mass. It has also been shown to help modulate hormone levels, particularly insulin, leptin, and adiponectin.
IF has been primarily studied for control of diabetes mellitus and polycystic ovarian syndrome, but is now receiving attention as a potential approach to cancer prevention or treatment. In vitro and in vivo animal studies suggest that PF inactivates pro-proliferative pathways, while enhancing differential stress resistance in normal cells.
In addition, other studies have shown that fasting induces autophagy and can modulate the immune system by activating CD8 cytotoxic T cells and inhibiting T-regulatory cells.