Obesity is a general medical condition, defined clinically by a body mass index (BMI) greater than 30 kg/m2 and is associated with increased risk of cardiovascular disease, type II diabetes, cancer and poor quality of life (National Center for Health Statistics 2007; Ogden et al. 2007; Kopelman 2000). The National Center for Health Statistics reports over 34% of American adults are obese with another 34% meeting criteria for being overweight (National Center for Health Statistics 2007; Ogden et al. 2006). Although increase in energy intake with reduced physical activity contributes to the increase in obesity, genetic factors have consistently been demonstrated to influence individual differences in BMI, with twin and family studies estimating heritabilities of ∼0.70 (Maes et al. 1997; Silventoinen and Kaprio 2009).
