Obesity is defined as an accumulation of excess fat in the body. It is a condition in which the total energy reserve, stored in the fatty tissue of humans and other mammals, is elevated to a point where it is associated with certain health problems or increased mortality. Eating too much leads to fat being stored in the body and overeating causes weight gain, and eventually obesity. Obesity is an epidemic in the United States and other developed countries. More than half of the Americans are overweight. Weight loss is an important step towards getting rid of the possible complexities of obesity.