Obesity results when body fat accumulates over time as a result of chronic energy imbalance (calories consumed exceed calories expended). In recent decades, obesity has reached epidemic proportions in many populations whose environments offer an abundance of calorie-rich foods and few opportunities for physical activities. Obesity is caused by a complex interaction of the environment, the genetic predisposition, and human behavior, but the relative contribution of these factors is still poorly understood. Environmental factors are major contributors to the obesity epidemic. In addition to environmental factors, there is genetic predisposition to obesity. Although changes in genetic makeup of populations may not be fully responsible for this rapid rise in obesity, genetic predisposition does play a vital role in the development of obesity. Genetic factors are estimated to account for >40% of the population variation in BMI [7, 8]. Thus, genes influence how our bodies capture, store, and release energy from food.
