A food craving (also called selective hunger) is an intense desire to consume a specific food, and is different from normal hunger. It may or may not be related to specific hunger, the drive to consume particular nutrients that is well-studied in animals. In studies of food cravings, chocolate and chocolate confectioneries almost always top the list of foods people say they crave; this craving is referred to as chocoholism. The craving of non-food items as food is called pica. Causes A food craving is a strong desire to eat a particular type of food. This desire can seem uncontrollable, and the person’s hunger may not be satisfied until they get that particular food. Food cravings are common. One research found that 97% of women and 68% of men reported experiencing food cravings. There is no single explanation for food cravings, and explanations range from low serotonin levels affecting the brain centers for appetite to production of endorphins as a result of consuming fats and carbohydrates. People often crave energy-dense foods: chocolate is the most frequently craved food, followed by other sweet and savoury foods which are high in calories. Foods with high levels of sugar glucose, such as chocolate, are more frequently craved than foods with lower sugar glucose, such as broccoli, because when glucose interacts with the opioid receptor system in the brain an addictive triggering effect occurs. The consumer of the glucose feels the urge to consume more glucose, much like an alcoholic, because the brain has become conditioned to release "happy hormones" every time glucose is present. Cultural differences have been found, for example, with rice being the most frequently craved food in Japan. Among low-calorie foods, cravings for fruits are common. Food cravings tend to occur in the late afternoon and evening. The desire to eat high-calorie foods increases throughout the day, while craving for fruits decreases. The aspect of a food craving is multi-dimensional. Physiologically, it is connected with several mechanisms that motivates food seeking and prepares the body for digestion such as increased salivary flow along with activating reward-related brain areas such as the striatum. Cognitive (i.e., thinking about the food) and emotional (e.g., desire to eat or changes in mood) components are also involved. A final behavioural aspect of seeking and consuming the food also occurs. Whilst experiencing a food craving often results in eating the craved food, the craving-consumption relationship also