Starvation occurs when there is no food intake for an extended period of time. In the context of this article, starvation and starvation diets will refer to intake of no calorie-containing food or beverages for periods of more than 24 hours. Semistarvation refers to energy intakes that are chronically and substantially below what is required to maintain body weight. This is a condition found in concentration camps, during famine, and during conscious restriction of calorie intake to very low levels. One feature of fasting to the point of starvation, as in famines, is that this condition reduces the risk of developing chronic diseases such as obesity and diabetes, which are a consequence of the surfeit of nourishment in today's societies.