Obesity, also known as adiposity, is a chronic metabolic disorder caused by an excessive accumulation of fat in the body or abnormal fat distribution. The exact causes of obesity are not clear, but it is generally believed to be the result of the interaction of multiple factors including environmental and genetic factors. In terms of environmental factors, there is a tendency for obesity to cluster in families; individuals with one or both parents who are obese have a significantly increased likelihood of being obese themselves. The second factor is environmental influences. Consuming more calories than are expended is the primary cause of obesity. Additionally, sedentary lifestyles, lack of physical exercise, and insufficient physical activity all contribute to reduced energy expenditure, leading to obesity. Poor dietary habits, such as eating large portions, a preference for sweets, or oily foods, also increase calorie intake and contribute to the occurrence of obesity. Furthermore, genetic mutations can also lead to obesity. Another viewpoint suggests that childhood obesity can increase the incidence of adult obesity, with people who were obese after the age of six having a more than 50% chance of being obese in adulthood.